But when they met with the Chandlers and saw their pain, the students said they wanted to help.

Sarah Hartman: Who lived the life that we led for two years as Hope College students.

Victoria Corderi: This was someone your age...

Sarah Hartman, student: I was frightened to begin with. Something totally out of reality it felt like.

At the time, no one could have imagined the far-ranging impact that documentary would have. In fact, in the beginning, some of the students thought the project wasn't such a great idea.

Professor Schock: Not to solve the case, but to tell the story about this case.

But in 2003, the Chandlers discovered someone who did remember Janet. They were approached by Professor David Schock and his students at Hope College -- the same Christian school Janet had attended. They wanted to make a documentary about the unsolved case, marking the 25th anniversary of Janet's death.

And Janet Chandler was all but forgotten.

But no witnesses came forward. No one talked.

The Chandlers have always believed someone from the motel must have seen something -- or heard -- something the night Janet was abducted. Not just the killer, but maybe others, too, were keeping a terrible secret. And police investigators were convinced someone was holding something back.

Jim Chandler: I didn't expect it to go on and on. I figured they'd have it solved years ago.

The brutal murder stunned the quiet, lakeside town of Holland. The police launched an intensive investigation, at one point focusing on some local men who had done some bar room bragging about being involved. But to the Chandler's surprise, no arrests ever were made.

The Chandlers say after that day, they never listened to Janet's recordings again -- that it was too painful.

Janet's recording of 'My Jesus' was played at the service.

Jim Chandler: In fact, she sang at her own funeral.

Janet's funeral took place in the same church where she had sung in the choir.

Jim Chandler: You're just numb … You just can't believe that something like that could happen, you know.

"It wasn't until noon that the Hope College music student's parents were brought down to South Haven to identify the body as that of Janet Chandler."

A day later, a snow plow driver turned into a highway crossover south of Holland and spotted something buried in the snow. It was the naked and battered body of a woman, thrown away like road-side trash.

Dennis Chandler: I just got in my jeep and drove to Holland and started driving all the back roads. My dad did the same thing.

The Chandlers were frantic. Jim Chandler and his son, Dennis, searched for Janet all night.

"It was just after 2 o'clock Wednesday morning when the Blue Mill Inn was robbed of about $500 and hotel clerk Janet Chandler was missing from the office..."

Her parents' worst fears about that motel job were realized in the early morning hours of Jan. 31.

Jim Chandler: We tried to get her not to take that. Even then, a night clerk job at a motel wasn't the safest place to be.

Back in 1979, Janet Chandler was a 22-year-old music student at Hope College, in Holland, Mich. She was working nights as a desk clerk at a local motel.

And they have had to live with the bitterness of knowing someone had gotten away with it.

"You'd have thought after all this time you'd be able to talk about it, as you can tell, it's still hard," Jim Chandler told Dateline.

For almost three decades, Jim and Glenna Chandler have lived with the overwhelming grief of losing their daughter.

Victoria Corderi: What was it about that meeting that turned it around? Jon Johnson, student: Seeing them bring out a trunk they hadn't brought out in 25 years, with all the letters and the pictures of her. At that point you kind of become... I want to do it for them.

It was easy to see why the students were so taken with the Chandlers. When we met them, they told us about Janet.

Victoria Corderi: Is she frozen in your mind as a little girl, or how she was when she was 22? Jim Chandler: As a little girl, I guess. Glenna Chandler: She was easygoing and happy-go-lucky. And she lived a sheltered lifestyle. We are Christians, and she was brought up in the church. And all her friends were friends from church … Every time her girlfriend would get married, we'd go to the wedding. It was hard. Victoria Corderi: So you would imagine your own daughter, this what she should have been doing. Getting married, having children? Glenna Chandler: Right. Jim Chandler: I don't think there's a day that went by -- hardly an hour … Victoria Corderi: That you didn't think about her? Jim Chandler: Yes.

The students did their own interview with the Chandlers for their documentary.

Glenna Chandler: A parent never expects their children to go before them. You learn to live with it. That's about all you can do. One day at a time.

And they met Dennis, Janet's younger brother.

Dennis Chandler: Well, she definitely knew where she was heading. She believed in God...

The students said the experience left them a bit shaken, but even more committed to finding out what happened -- and who might be keeping silent about Janet's murder.

Kyle Shepard, student: That happened a whole lifetime ago. And then it just really puts a lot of things into perspective for you. She didn't get to live her life.

And so they began to document Janet's life and death, by first going back to Jan. 31, 1979: the night of Janet's murder.

Just after 2 a.m., police received a call from the motel where Janet worked, the Blue Mill Inn.

(911 call) "I have reason to believe that there might be a robbery in progress down in the office or the lobby."

Holland police detective Jim Fairbanks had raced to the scene.

Det. Fairbanks: It had been a robbery. We could determine that. And it was also very clear that the clerk was missing.

Of course, that missing clerk was Janet Chandler.

Fairbanks said Chandler's jacket was still on the chair, and her Salem cigarette still smoldered in the ashtray.

Fairbanks interviewed the man who had called 911, Robert Lynch., but Lynch said he had seen nothing.

The motel was full of guests that night, but Fairbanks said he could not find a single eyewitness. The students wondered: how could no one have seen or heard the abduction ?

Amy Schlosser, student: How did they get her into the car? How was she taken without anyone hearing her scream or put up a fight? Did she know this person? So then we began to question: were there two people involved? Were there multiple people involved?

The students say perhaps their toughest assignment was visiting that desolate highway turn-off where Janet's body had been dumped in the snow, and seeing the crime scene photos. Those photos showed Janet had been strangled with some kind of rope, wire or belt.

Student: It made it a lot more real.

And the more the students learned about the crime, the more questions they had. When had Janet been killed? Was it just hours after the robbery, or was it closer to 24 hours later, when her body was found? And if she'd been alive for 24 hours, what happened to her after the abduction?

Victoria Corderi: Were you sitting around, discussing the theories? Sarah Hartman: We became investigators. We went from college students, everyday classes, to investigators.

But 25 years after the murder, could a group of students begin to untangle the mystery that the police could not solve? Could they find out who killed Janet Chandler?

The student documentary "Who killed Janet Chandler?" opened at the Knickerbocker Theater in Holland, Mich., just days shy of the 25th anniversary of her murder.

Amy Schlosser, student: It was just very emotional for everyone. She had become real to me. And I think that she had become very real in the hearts and minds of everyone.

The students had brought Janet Chandler's story back to life, but were no closer to solving the crime than the police had been 25 years earlier, no closer to figuring out how a young woman could be abducted and murdered without a single person seeing or hearing a thing. And yet the documentary was about to light a candle of justice.

Professor Schock: All along, one of our hopes and prayers was perhaps we could stir enough interest for a renewed investigation.

Professor David Schock had been lobbying the police to use his students' documentary as a jumping-off point for a cold case investigation. But it wasn't an easy sell.

Lt. John Slenk: Quite frankly, initially, I was hesitant to do it because I knew that it was going to involve a tremendous amount of time.

John Slenk heads up the state police cold case unit for southwestern Michigan. One big negative in this case, he says, was the fact that modern technology was not going to help solve it.

Victoria Corderi, Dateline NBC: No DNA? Slenk: There was physical evidence, but that physical evidence didn't bring any real value to this investigation.

The case would hinge on tracking down witnesses and getting them to talk. No one had talked in 25 years, but investigators hoped the publicity generated by the documentary might encourage witnesses who'd kept silent in 1979 to come forward now.

Victoria Corderi: You think people change with time? Slenk: It does change with time, because circumstances in people's lives change with time.

And like the Chandlers, Slenk believed someone out there knew the truth. He assembled what he called a dream team of investigators: detectives Dave Van Lopick, Mike Jafri and Geoff Flohr from the state police. And detectives Rob Borowski and Roger Van Lier from the Holland police. They began by learning everything they could about Janet Chandler.

Lt. Slenk: We find oftentimes that the more we get to know about the victim, the more we understand the victim. The victim will oftentimes, even in death, point us to their killer or killers.

The cold case team went all out, casting a wide net to find Janet's old friends and co-workers. And Det. Jafri said they used the student documentary to jog memories -- and perhaps stir some guilt.

Mike Jafri: That tape was probably played in 40 states at all hours of the day and night for different interviews.

One of their first interviews was with Janet's old roommate, Laurie Swank. Swank was also Janet's boss at the motel, but was not working the night of the crime. They showed her a clip from the documentary, and Swank -- even after all these years -- appeared to be deeply affected.

Laurie Swank: It made me physically ill. What could she have done to deserve to have this happen to her?

Yet Swank said she knew nothing and saw nothing that could shed light on that horrific night.

The cold case team also tracked down a group of former security guards who had been living at the Blue Mill Inn in late 1978 and early 1979. The men had been in town to police a bitter strike at a chemical plant. But the strike ended soon after Janet Chandler's murder. Detective Roger Van Lier said the police never had a chance to question them all.

Victoria Corderi: These guys, who were transients anyway, left town. Van Lier: Left town. Went to their home state. Went to other strike details, other duties.

Could any of these security guards have seen what happened to Janet? In interviews, most of them said they barely remembered Janet, or didn't know any details about the abduction and murder.

Det. Dave Van Lopick: The guards basically said, "We worked 12 hour shifts and we just crashed at the motel. We didn't do anything other than work and eat and sleep."

With no one talking, the investigation seemed to be at a dead end after more than a year of work. But everything was about to change.

Victoria Corderi: What was the first big break? Det. Rob Borowski: When we interviewed Glenn Johnson in Minneapolis.

Johnson was a former guard who lived at the Blue Mill Inn. He said he'd heard a rumor, just a rumor, that a guard named Robert Lynch was involved in Janet's murder.

The cold case team had heard Lynch's name before. Remember that 911 call?

(911 call) "I have reason to believe that there might be a robbery in progress down in the office or the lobby."

It was made by Robert Lynch. Detective Geoff Flohr listened to that call again, and something about it seemed phony.

Flohr: This sounds staged to me. There's no emotion.

The team brought Lynch in for questioning and found him evasive.

Det. Van Lopick: We came away from that interview believing there was more involvement on his part than what he was telling us.

Now the cold case team felt it had its first possible lead, and the detectives went after anyone who had been close to Lynch back in 1979, once again showing clips from the documentary.

Victoria Corderi: Do you remember anyone in particular who had an emotional response to seeing it? Flohr: Harry Keith.

Keith had been Lynch's roommate at the Blue Mill Inn, and he saw something in that documentary, something that would lead to the discovery of key evidence in the investigation. It was a photograph of Janet. Keith told police he was the one who had taken it back in 1979, and he showed them other photos he'd shot during that time.

Det. Borowski: And this individual had a photo album full of photographs of parties, drinking -- things like that.

The Blue Mill Inn, the detectives soon learned, was party central for the guards, with a conference area set aside for big gatherings, and a rolling, room-to-room party that ran all hours of the day and night.

Lt. Slenk: It was a den of iniquity. And it was just a wild bunch of unsupervised people that were there to party, drink, use drugs, whatever. Get involved in sexual escapades, whatever their little hearts desired.

And there was Janet, a girl they said they barely knew, drinking, sitting on someone's lap, wearing a guard's uniform. Janet, the night clerk, police say, got a lot of attention from the men.

Lt. Slenk: And I think a lot through her naiveté, Janet got sucked into things at that motel that should have never happened.

Robert Lynch was in some of those pictures as well, and he was brought back in for questioning.

(interrogation tape) Geoff Flohr: Listen to me, all right? When you say to me you don't remember, I say bull.

Detective Geoff Flohr was the lead interrogator. He was brought on to the cold case team because of his skill at breaking down suspects.

Geoff Flohr: I've been taught and trained to listen to what people say. I listen to their linguistics. I'm a polygraph examiner. Victoria Corderi: So, how they put sentences together? Geoff Flohr: You betcha. Victoria Corderi: Choice of words? Geoff Flohr: You betcha … And you can start to utilize those when you break down the dam of denial.

In fact, Flohr had earned the nickname "The Closer" for his ability to break suspects, and now the closer went to work on Robert Lynch. He showed a clip of Janet's father, who appeared in the student documentary.

(interrogation) Geoff Flohr to Robert Lynch: you look at that dad, and that could just as easily be you sitting there. Do you understand? Lynch: Yeah. Flohr: You have children, right? Lynch: Yes, three. Flohr: You remember the first time you went somewhere with them and you lost them? Lynch: Yeah. Flohr: You remember that feeling you got inside your body? Now imagine, just imagine, Bob, what that would feel like when you're talking about a 22-year-old girl.

Lynch was affected by what he saw.

Flohr: I remember a slight tear in his eye, I remember a quiver in his lip ... Without a doubt.

And finally, under intense questioning, Lynch cracked.

Det. Dave Van Lopick: Mr. Lynch commented to Jeff and I, "Well, it was a party that went haywire." Victoria Corderi: Was that the first time you heard about a party? Det. Flohr: Yeah, pretty much. A party involving Janet.

But what really happened? The cold case team had discovered what appeared to be the scene of the crime from a real witness. With Lynch's revelation, a conspiracy of silence was about to unravel.

"Listen to me, I want you to tell me the truth, and I want you to tell me the truth right now," Geoff Flohr says to Robert Lynch in the interrogation tape.

The cold case team was trying to crack a 25-year-old conspiracy of silence surrounding the murder of Janet Chandler, but first they had to crack Robert Lynch. He'd told detectives Janet Chandler was at a party the night she was killed.

(interrogation tape) Flohr: I want you to tell me the plan about the party. What was the party supposed to be about? Lynch: I don't really know.

Over 18 separate interrogation sessions, Det. Geoff Flohr broke Lynch down, and Lynch finally revealed the truth about that party.

(interrogation tape) Lynch: It was all about Janice (sic).

And the truth about the murder plot was so elaborate and so unimaginable it even shocked these veteran detectives.

Lieutenant Slenk: It's difficult to understand or get into the mindset of someone who's willing to participate in that.

Robert Lynch said the conspiracy began to unfold the night of Jan. 31, 1979, at the Blue Mill Inn. He and another guard named Bubba Nelson told Janet there was a surprise party in her honor and got her ready to go.

(interrogation) Flohr: Tell me what you mean by ready. Lynch: By taping her eyes so she wouldn't know where she was going. In fact, he didn't even mess with her hands, he just said, "This is a surprise. We're going to go to a party."

According to Lynch, Janet left the motel calmly, expecting a surprise. It could be one reason why, perhaps, no witnesses had reported hearing a struggle. But what about that robbery? Police had found the motel safe open, and $500 missing.

In reality, Robert Lynch and Bubba Nelson were the robbers. They stole the money, then Lynch made that phony 911 call.

Janet was driven across town to a lakeside cottage where one of the guards had been staying, Lynch said -- the scene of the so-called party. Only after she was a prisoner in that cottage did she realize the frightening truth.

Det. Borowski: It wasn't a party, but a gang rape.

Now, Det. Geoff Flohr pushed Lynch even harder.

(interrogation) Flohr: I think you killed her, I think you know you killed her.

Finally, Lynch confessed to being one of the men who assaulted Janet, and strangled her with a belt.

Flohr: So when I say you had sex with her that day, that's the truth right? Lynch: Yes. Flohr: And when I say that you held the belt until she passed out and died, you checked her and she was dead, that's the truth? Lynch: But it wasn't intentional.

The lakeside cottage where the murder took place stood here. It was torn down years ago, but during his interrogation Robert Lynch vividly resurrected it and all the horrors that took place here.

He said while he and other guards were raping Janet in an upstairs bedroom, there was a party going on downstairs. Lynch said there were perhaps 25 partygoers, both men and women. No one stepped in to stop the relentless assault on Janet, and for more than 25 years, no one went to the police.

Victoria Corderi: How would you describe the men responsible? Det. Borowski: Evil. Det. Van Lopick: Cold. Det. Slenk: You have to be evil to do that, pure and simple.

Robert Lynch was arrested and charged with murder, but he still had one more surprise for the detectives. He said it wasn't just men who planned the attack; women were in on it as well.

(interrogation) Flohr: So put yourself back in that room, you got how many women? That are in the room during this planning. Lynch: Two or three. Flohr: Two or three women.

He said one woman in particular was intent on getting Janet.

Lynch: She played the role of being Janice's best friend. But actually I don't think she was. Det. Flohr: What was her first name? Lynch: I don't know.

So detectives started to track down Janet's girlfriends from 1979. Diane Marsman worked at the Blue Mill Inn with Janet. She too had kept silent for years, but under repeated questioning, she finally she opened up for the first time.

(interrogation) Marsman: I don't think she could have ran away. He was holding her, Bubba was.

Marsman said she'd watched from the balcony of the Blue Mill Inn that night when guard Bubba Nelson abducted Janet, and that she went to the party with another woman who worked at the motel, Cheri Ruiz.

Ruiz's admissions about the plans for Janet were even more shocking.

(interrogation) Cheri Ruiz: To strangle her, to torture her.

But remember, there was one women who Robert Lynch said was a primary planner. Finally, he remembered her name.

Van Lopick: He just mentioned that he remembered a female, Laurie.

In 1979, Janet's roommate was named Laurie Swank. She'd been the night manager at the Blue Mill Inn at the time of the murder. Remember, when police first questioned her, Swank had even professed grief and disgust at the crime.

(interrogation) Laurie Swank: How can you live with yourself, having knowledge of that? How can you live with it? I, I couldn't.

Detective Geoff Flohr, the closer, confronted Swank with Lynch's allegation.

(interrogation) Flohr: So the killer pointed the finger at you. That's how we came back here.

And after several more interrogations...

Flohr: You just have to tell the truth so that I know. Look at me. I've got to know.

The dam of denial started to break open.

Flohr: You saw Lynch kill her, didn't you? Just tell the truth. Swank: (no response) Flohr: Give up the battle. Just give up the battle and tell me you saw it.

And she finally admitted she was in on the gang rape plan from the start -- and was even there when it ended.

Flohr: You were there when she died, weren't you? That's why you ran. Come on. Come on. Swank: Yes!

The 25-year silence finally had been shattered. Laurie Swank told investigators the whole story: that she not only helped plan the assault, but witnessed it.

Swank: (sobbing) Dear God...

On Sept. 20, 2006, Michigan Attorney General Mike Cox announced that, in addition to Robert Lynch, five others were now charged with first-degree murder: Laurie Swank and former guards Carl Paiva, James ' Bubba' Nelson, Freddy Parker, and Tony Williams.

Cox: I have to say that the allegations here are as shocking and disturbing as I've ever seen.

After 27 years of freedom, the defendants were going to have to answer for what they did a lifetime ago.

Facing life in prison, Robert Lynch and Laurie Swank pleaded guilty. Both were sentenced to 20 years in prison, and both agreed to testify against their co-conspirators.

Lynch: I hope this brings the Chandler family some peace.

But there were still unanswered questions. Police now knew how she died. But why was Janet Chandler targeted in the first place?

The news that five people had been charged in the 1979 murder of Janet Chandler broke like a winter storm over western Michigan.

For Janet's parents, Jim and Glenna Chandler, the news was welcome -- and long overdue.

Victoria Corderi, Dateline NBC: What's the emotion? Is it happiness? Is it relief? Glenna Chandler: We're happy to hear that they're making some heading on it. Jim Chandler: That somebody's going to be held accountable.

By the time the police arrested the guards, many of the students whose documentary had helped to reignite the investigation had graduated from Hope College and had moved on.

Jon Johnson, student: I heard about it from an email from my mom, actually. And I was -- I didn't know really how to describe it at the time. Very happy.

But getting arrests and getting justice are sometimes two different things. The prosecution would be in the hands of Donna Pendergast, Michigan state assistant attorney general.

Donna Pendergast: What kind of people could do this to somebody? Victoria Corderi: Let me go through this. It's a 28-year old murder. Did you have any DNA? Donna Pendergast: No DNA. Victoria Corderi: Fingerprints? Donna Pendergast: No, we didn't have those either. Victoria Corderi: Sperm? Donna Pendergast: No. We had no samples that we could compare to any of the defendants.

The prosecution would have to rely on the credibility of its witnesses -- but that much-anticipated witness, Robert Lynch, would not be among them. He suffers from alcohol-related dementia.

Donna Pendergast: And I simply did not find him credible enough to put in front of a jury and say I, as prosecutor, am asking you to believe this.

Instead, the prosecution would rely on the women who saw what had happened to Janet Chandler: the friends who had betrayed her, starting with Laurie Swank.

She was Janet's roommate and had once professed to be Janet's best friend. Swank testified that Janet was popular with the guards staying at the Blue Mill Inn. And that, it turns out, had a lot to do with why Swank began to hate Chandler.

Donna Pendergast: Did Janet's relationship with the guards create any problems with you on a personal level? Laurie Swank: Yes. Because I became jealous. She was more popular. I was less popular.

Swank testified that in January 1979, she had a crush on defendant Carl Paiva, the supervisor of the guards. But Janet was in the way.

Pendergast: What kind of relationship did Janet have with Carl Paiva? Swank: A sexual relationship.

It was a classic love triangle. Laurie wanted Carl; Carl wanted Janet; and Janet was playing the field, which made Carl -- and some of the other guards -- angry. Swank admitted she would tell Paiva about Janet's alleged sexual escapades.

Donna Pendergast: Why did you give this information to Mr. Piava? Laurie Swank: To anger him. Make him think less of Janet. Donna Pendergast: How would he react? Laurie Swank: He would get angry, frustrated. He got upset. Donna Pendergast: Did he ever say anything that he intended to do in regards to this information? Laurie Swank: He would take care of it.

Carl Paiva "took care of it," Swank testified, by coming up with a plan to humiliate and punish Janet. She said other guards Janet had dated, and then dumped, also were in on the plan.

Laurie Swank: Janet thought a lot of herself. And it was mentioned she would be brought down a few notches. Teach her a lesson.

Swank said the plan was for Bubba Nelson to take Janet to the cottage where Carl Paiva was housed during the strike. Then Robert Lynch would stage the robbery at the Blue Mill Inn and make that phony 911 call to the police. Janet was taken away around 2 a.m. and held at the cottage until the party started the next afternoon.

Ms. Pendergast: Tell the members of the jury why you went to Mr. Paiva's residence. Laurie Swank: I went to see what they were doing to Janet.

Swank testified to the assault on Janet in graphic detail.

Laurie Swank: Janet was being raped.

Swank described a depraved scene: she said there were spectators in the room who actually cheered on the rapists, and there was even someone taking pictures of it all.

Ms. Pendergast: What did you do in that bedroom, Ms. Swank? Laurie Swank: I was part of the cheering section. Ms. Pendergast: What were you doing? Laurie Swank: I was looking at Janet. I called her a bitch. I encouraged the activity. Ms. Pendergast: Ms. Swank, I have to ask you because I know the jury's thinking right now -- what was going through your head? Why for God's sake were you participating in this? Laurie Swank: I was angry, jealous. Ms. Pendergast: How did you justify this to yourself? Swank: I can't.

And Swank admitted she was there for Janet's last, agonizing moments.

Laurie Swank: And all of a sudden I heard somebody say, she's dead. Laurie Swank: She was motionless. Ms. Pendergast: What did you do? Laurie Swank: I ran.

Witnesses Cheri Ruiz and Diane Marsman say they looked into that torture chamber as well, and backed key portions of Swank's testimony. But if they truly had any remorse about what happened, why had they stayed silent for so many years? Diane Marsman said it was because Bubba Nelson had threatened her at the time of the assault.

Prosecutor Buntz: Do you remember what Bubba said to you? Diane Marsman: That -- not to say anything about what happened, to keep our mouth shut or it could happen to us.

And Cheryl Ruiz also said she had been threatened repeatedly.

Cheryl Ruiz: Bubba did. And Carl did. Told me to shut my mouth. That we're going to do the same thing that they did to Janet to me.

And it wasn't only threats that ensured the code of silence. There were those photos. A guard named Ron Wirick testified that Carl Paiva had directed him to take pictures that night.

Donna Pendergrast: And did you start taking pictures of these sexual acts? Ronald Wirick: Yes.

Wirick said everyone at the party knew Paiva was holding on to those pictures and could use them against them if they went to the police. The pictures never were found.

In her closing argument, Donna Pendergast asked the jury to consider Janet's suffering, and the cover-up that had kept this crime secret for so long.

Pendergast: For 28 long years, there has been a conspiracy of silence about the horrific murder of a young girl.

And that conspiracy of silence has been unraveled by the evidence in this case.

The 1979 murder case of Janet Chandler finally was in the hands of the jury....and as Jim and Glenna Chandler awaited the verdict, they say memories of their daughter came flooding back.

Her beautiful voice. Her playful personality. And the incredible loss they had endured for so many years.

In court, the usually stoic Glenna was emotional and apprehensive.

The jury came back with a verdict on the second day.

Judge: People of the state of Michigan versus Arthur Paiva. As to count one, what is your verdict? Foreman: Guilty of premeditated, first-degree murder.

Arthur 'Carl' Paiva was found guilty of first-degree murder. The three other defendants were found guilty of second-degree murder, and guilty of additional charges. All four now faced life in prison. Jim Chandler softly whispered "amen."

Victoria Corderi, Dateline NBC: When you heard the verdicts, guilty-- guilty-- guilty-- what was that moment? Glenna Chandler: Well, it was relief, that's for sure.

Jim Fairbanks was the first detective on the case 28 years earlier. He had pushed hard for the cold case investigation.

Fairbanks: It's something I never forgot. Jan Chandler was in my mind since it happened. Schock: I think we have achieved justice and I'm so grateful.

Former Hope College Professor David Schock celebrated as well. He and his students had helped to revive the investigation with their documentary.

Before, during and after this trial, one question haunted those who knew the story of Janet Chandler's murder. Even taking the threats into account, how could so many people keep such a terrible secret for so long?

After the verdict, we explored that question. Why, in 25 years, had no one ever called the police? Why had so many people gone along with the conspiracy of silence?

Donna Pendergast: Some had to do it in the interest of self-interest. And others, well, feared culpability. Victoria Corderi: So you understand why they kept silent. Donna Pendergast, prosecutor: Right. Victoria Corderi: You don't understand how they kept silent. Donna Pendergast: How do you live with yourself? How do you go on with your life knowing you participated in something like this?

Two of the witnesses who had kept silent about Janet Chandler's murder, Cheri Ruiz and Diane Marsman, agreed to talk to Dateline.

Victoria Corderi: You knew that they were talking about doing this to Janet. Why didn't you say anything to Janet? Diane Marsman: I'd say probably fear. I never expected them to kill her. I didn't think she would die. Victoria Corderi: Did you ever look at each other and say "Let's try to stop this?" Cheri Ruiz: We couldn't. Diane Marsman: Yeah. Cheri Ruiz: All these men. And then it was just us two. There's no way. Diane Marsman: You just couldn't stop it. Victoria Corderi: Go to a phone and call the police. Have somebody break this up. Why was that not an option? Diane Marsman: You could see what they were doing and that was kind of a fear thing. Right? We'd seen what they did to her. Cheri Ruiz: They're going to do it to us.

The women say they kept in touch with each other sporadically through the years.

Victoria Corderi: Did you ever say to each other, "We should call the police now. It's been a few years"? Or send an anonymous note? Cheri Ruiz: They're not going to believe us. They will not believe us. Victoria Corderi: Do you feel at all that you victimized Janet? Cheri Ruiz: No. Victoria Corderi: By your silence? None? Cheri Ruiz: No. Not at all. Victoria Corderi: By allowing these guys who brutalized and raped her to walk around, live lives, have families for 28 years? Diane Marsman: Yeah. I do, I think. Victoria Corderi: Do you feel shame about keeping quiet? Or having been there in the first place, and not done anything? Marsman: Probably both. And not being able to do anything to help her.

But while Marsman regrets not speaking out, she says other people should not be so quick to judge.

Marsman: They didn't walk in our shoes. They don't know us. They don't know what we've been told. Ruiz: Yeah. Marsman: That fear grips you.

Lt. John Slenk, who supervised the cold case investigation, says he does understand.

Lt. Slenk: When you're a 21-year-old young lady and you watch one of your friends -- and I use that term loosely -- being raped and murdered, and then the guys that did it said to you, "You talk, that's what you get"? What would you do?

Geoff Flohr, the cold case team closer, doesn't buy it.

Flohr: I wouldn't let them off the hook at all. And you know why? Because everybody felt a level of guilt. Victoria Corderi: So you think it was guilt that kept their mouth shut. Flohr: She was kidnapped. It was staged. And they knew what was going to happen to her. She was going to be taught a lesson. So why are those people there? To watch that unfold. And did any one of them try to warn Janet? Not a one of them.

The four men convicted of murdering Janet Chandler would be sentenced a few weeks after the trial. It would be the final stop on the Chandlers' long journey to find their daughter's killers, and, perhaps, some peace.

Though their daughter's killers had been found guilty, there still remained one more heart-wrenching task for Jim and Glenna Chandler: speaking at the sentencing.

They meekly approached the microphone.

"Glenna and I have been waiting for 28 years for this day," said Jim Chandler.

"They thought they got away with it, and for the most part they did. But because of the hard work and dedication of the cold case team and others, they've finally been brought to justice."

Glenna Chandler said, "I thank you for upholding the laws of the land and the jurors for seeing the true evidence in returning a verdict of guilty of the torturing and murder of our beloved daughter."

One by one, the four convicted men shuffled to the podium to hear their sentence. Carl Paiva.

Judge: It's the sentence of the court that you be turned over to the Michigan Department of Corrections to serve the term of life without parole.

All four men were sentenced to life without parole. It was a bittersweet victory for the Chandlers.

Glenna Chandler: And we just thank everybody. We're just glad it's behind us. It's almost 30 years. That's a long time.

And Jim Chandler offered thanks to the cold case team.

Jim Chandler: They went above and beyond their expected duties, even putting flowers on the grave.

There had been a picture of Janet posted in the homicide division of the Holland police for 28 years. Now it could come down. The prosecutor says she also kept a picture of Janet nearby through the trial .

Donna Pendergast: I do. Every case. And it will probably sound weird, but I talk to it, too. I mean, it's -- you know, I can't tell you how many times during this case and other cases, it's like, we're going to get them. We're going to get them, Jan. And we did.

The Chandlers came by when we were interviewing David Schock and his students to thank them personally for the documentary that touched the conscience of a community -- and sparked the investigation that finally caught Janet's killers.

For the students, the experience of seeing their class project grow into a major prosecution was a life-changing experience.

Student: I learned to appreciate life a lot more, that's for sure. I mean, the more you research death, the more you appreciate living day after day. Sarah Hartman, student: It's knowing that you can make an impact. And you can do something that seems so small at the beginning. And at the time when the idea was proposed. And it turned out to be something like this. You never know what's going to happen.

Later, with David Schock and the family, the Chandlers celebrated their 54th wedding anniversary, and remembered that had she lived, Janet would have been 52 years old.

Victoria Corderi: Do you think there was justice for Janet? Glenna Chandler: Yes, for Janet. These other ones have to live with what they did. But, we know where she's at and we know that she's with our Lord. Victoria Corderi (to Jim Chandler): Do think there was justice? Jim Chandler: No. Victoria Corderi: Not when you've lost your daughter? Jim Chandler: No. There's closure, but I don't think there will ever be justice.

For 28 years, the Chandlers had been in the dark about the fate of their daughter. Now they knew all the facts of Janet's last, painful hours. But the most important fact had not changed.

The morning after the sentencing, in a freezing rain, Jim and Glenna made a short drive to Janet's grave.

At the grave, Mr. Chandler said "Thank you, Lord, for bringing us closure, for the conviction of these criminals."

Mrs. Chandler said "Someday, Jan, we'll all be together."

You may wonder, with so many people involved in Janet Chandler's death, why more were not charged. Prosecutors say they had to make tough choices, but in the end decided to charge only those with the strongest evidence against them.