Produced by Judy Rybak, Lindsey Schwartz, Elena DiFiore, Chris O'Connell and Gregory McLaughlin

[This story previously aired on November 9, 2019. It was updated on June 27, 2020.]

When Carol Dodge's daughter Angie was murdered in the summer of 1996, she thought the killer would be brought to justice quickly. Idaho Falls Police had his DNA -- a pristine sample.

But for nearly two decades police couldn't find a match to the DNA, so in 2014, then-case Detective Patrick McKenna searched a small DNA database owned by Ancestry.com, which used to be public, and got a hit.

Get Breaking News Delivered to Your Inbox Click here to view related media. click to expand

"It led us to this Michael Usry Jr. who just happened to be a filmmaker," Dodge tells CBS News correspondent Anne-Marie Green.

"'Murderabilia' got me the reputation of being a person who is really into murder," Usry Jr. says of his short film.

Usry Jr. turned out not to be the killer and joined with Dodge's mother to search for the man who left his DNA at the scene.

IN SEARCH OF A KILLER

Carol Dodge: Grief has no time limit … I just can't, I can't let go. … I can't let go of her.

Carol Dodge lost her daughter Angie when she was just a teenager.

Carol Dodge: She was just discovering who she truly was … and wanting independence. … she says … "Just let me grow up. … Let me make my own mistakes. You know, you don't need to watch me, you know, you don't need to be my shadow."

Carol Dodge has been relentless in the search for her daughter's killer. "For 23 years, I've traveled every road there is ... turned every stone there is, to find justice for my daughter." Carol Dodge

It was the summer of 1996 in Idaho Falls, Idaho, a mostly Mormon community, where neighbors knew each other by name, and doors were rarely locked, says former Chief of Police Mark McBride.

Chief Mark McBride: It was a very, really a very quiet, peaceful town overall.

Just three weeks before her death, 18-year-old Angie got her own apartment.

Carol Dodge: I saw her the night that she was killed. … She said, "It's so hard growin' up." … and she laid her head on my shoulder and we just kinda — rocked back and forth. And … I'm so grateful for that moment … extremely grateful that [crying] my last words were that I love her.

The next morning, Angie didn't show up for work at a local beauty supply store.

Chief Mark McBride: We got a phone call at our 911 center about 11:00 in the morning … and one of her friends at work — came to check on her … and the door was unlocked. She went in and she found a body laying there on the floor … and a very bloody crime scene.

There was no sign of forced entry, but there were signs of a struggle.

Anne-Marie Green: You think she fought for her life?

Chief Mark McBride: Yes, I do.

Angie was stabbed and cut 14 times and left half naked. The killer ejaculated on her, leaving behind what DNA expert Greg Hampikian calls "a pristine profile."

Greg Hampikian: It's a single profile, complete identification. One man to the exclusion of everyone on the planet.

Police began collecting the DNA of dozens of local men and spent months interviewing everyone Angie knew, including Christopher Tapp. Although his DNA didn't match, and Tapp denied any involvement, after more than 28 hours of interrogation over 23 days, Tapp confessed to participating in Angie's murder.

COP: You were there correct? CHRIS TAPP: Correct.

Anne-Marie Green: Did you know Christopher Tapp?

Carol Dodge: No. Didn't know — had no clue.

Tapp told police that the night of Angie's death he and two friends stopped by her apartment. During an argument, Tapp claimed one of his friends started stabbing Angie while he held her down.

COP: You're holding her down, OK, while she's being cut. You're holding her down while she's being – CHRIS TAPP: — cut.

But when Tapp went before a judge, he pleaded not guilty of raping and murdering Angie Dodge.

Carol Dodge: I said, "You beast. You horrible beast … How could he do this to my daughter?

The defense argued Tapp's DNA didn't match the killer's, but on May 28, 1998, it took the jury approximately 13 hours to reach a verdict: guilty.

Nearly two years after Angie Dodge was murdered, Chris Tapp faced his punishment with Carol Dodge glaring at him.

SENTENCING JUDGE: You are guilty of the crimes of murder in the first degree and rape.

His sentence: 30 years to life. But the murder of Angie Dodge was still an open­ case. Chris Tapp did not match the DNA and he wouldn't tell police who did.

Carol Dodge: I just couldn't understand why he would go to prison and take a life sentence and not give the other person up.

Tapp did give authorities several names, including someone named "Mike":

DETECTIVE: How sure are you that his first name is Mike? CHRIS TAPP: I'm dead pos — positive.

But police could never make a DNA match. So, the case went cold — but not for Carol Dodge.

Carol Dodge: I never stop looking for the actual person who matches the DNA.

By 2009, the killer's DNA had been entered into the national criminal database — known as CODIS — but there was still no match. So, Carol called well-known DNA expert Greg Hampikian.

Greg Hampikian: I had this message. … "They don't know who killed my — my daughter."

By then there had been many advances in DNA technology, and with Hampikian's help, Carol pushed authorities to use a new controversial search process called, "familial DNA." It looks for anyone who may be related, to Angie's killer.

Greg Hampikian: … which means going into that database in Idaho, of the convicted offenders, and looking for a family member that might match this DNA partially.

Idaho doesn't allow familial searches in their criminal database—so Hampikian made an even more controversial suggestion: a familial search through public databases.

Carol Dodge: I'm the one that went to the Idaho Falls Police Department and the prosecution saying … "we need to do this."

Imagine you are one of millions of Americans to open up a DNA test kit, spit into a test tube and then send your DNA off to a commercial database. Well, now that database owns your DNA profile, and you may not realize it, but police may be able to access it.

Chief Mark McBride: We're interested in solvin' a crime and we're gonna use any technique we can … that we can legally use.

In the summer of 2014, detectives searched a public DNA database owned by Ancestry.com — they got a hit.

Greg Hampikian I was told they got 34 out of 35 markers I believe.

Anne-Marie Green: Is that good?

Greg Hampikian: Yeah. That's — that's a good investigative lead.

It was a close enough match to make Detective Patrick McKenna think they had found a relative of Angie's killer. So, police got a warrant for Ancestry.com to reveal his identity: it was a man named Michael Usry Sr.

Det. Patrick McKenna: We know it's not that individual or we would have had 35 out of 35 on that so that's when we started doing research into the family.

That led investigators to suspect Ursy's son, Michael Usry Jr. Detective McKenna wondered if this could be the Mike that Chris Tapp once named.

Det. Patrick McKenna: And then we started researchin' him … and the films that he was making … it was a little eerie to — try to think that that could possibly — possibly be a solid suspect in the case.

HOW A FILMMAKER BECAME A SUSPECT

Anne-Marie Green: I have to ask you this question

Mike Usry Jr.: Yes.

Anne-Marie Green: Do you have a particular interest in murder?

Mike Usry Jr.: I — I don't have a particular interest in murder. You know —

Anne-Marie Green: It sure seems like it, based on your film projects.

Mike Usry Jr.: I know, it does. But no, I — I really have quite an aversion to it.

But authorities investigating the brutal murder of Angie Dodge weren't so sure.

Mike Usry Jr.: Precisely at 2:00, three — gentlemen came to my door

In December 2014, more than 18 years after Angie's murder, Michael Usry Jr. was living in New Orleans when two detectives from Idaho Falls and a Louisiana State police officer brought Usry to a state police office near the New Orleans Superdome and started grilling him.

Mike Usry Jr.: They said, "So what about — your travels to Idaho. Have you ever been to Idaho?" … and I had, in fact … I actually went up there with some friends for just one night.

He was 19 years old back then, and he and his friends drove to Rexburg, Idaho, passing right through Idaho Falls.

Mike Usry Jr.: Well, they were really interested in that.

Det. Patrick McKenna: We were — a little surprised that we were … were able to actually place him in Idaho Falls.

It was a big red flag for Detective Patrick McKenna.

Mike Usry Jr.: It's kinda weird. But I just really didn't — didn't get it.

Then one of the officers pulled out a warrant and swabbed his cheek for DNA.

Mike Usry Jr.: At that point, I went, "Hey, what — what's goin' on here, you guys? Should I get a lawyer?"

Once they had his DNA, they drove Michael Usry home without any explanation.

Mike Usry Jr.: I just basically stood on my sidewalk in a daze.

It was a call to a close friend that finally shed some light.

Mike Usry Jr.: And ah, he said, "Well, what's the case? What is this?" … And I go, "Well, they wouldn't tell me anything except that it was a high-profile murder case in Idaho Falls." … So, he gets on the computer. … And within 20 seconds he's like, "Oh yeah, this is the case right here. It's some girl named Angie Dodge."

Mike Usry Jr., a filmmaker whose movie featured a convict describing how he stabbed a woman to death, was now suspected of doing just that to Angie Dodge. CBS News

The filmmaker whose movie featured a convict describing how he stabbed a woman to death was now suspected of doing just that to Angie Dodge.

Mike Usry Jr.: I mean it was very much a case of an overkill. They stabbed her and cut her and it was just … butchery … people were like, "Wow … what does this imply for your career … for your life, for your family? For your family's name?"

Usry remembers being terrified, spending days holed up at home worried what police would do next.

Mike Usry Jr.: … pretty sure that they were tapping my phone calls — possibly staking me out … certainly checking my computer searches.

But Usry knew he hadn't killed anyone, and he wanted answers. A local newspaper reporter showed him a copy of the warrant investigators used to obtain his DNA. And right there — the answer to the question "why him?" dated back about 17 years.

Mike Usry Jr.: And I went, "Wow, this was because of my dad."

The filmmaker's father, Michael Usry Sr., participated in a genealogy project at his local church. A sample of his DNA went to that public database which was later purchased by ancestry.com. And that's where police came across it.

Mike Usry Jr.: There are 34 out of 35 alleles that match … It seems shocking to me.

Thirty-four out of 35 DNA markers sounds like a stunningly close match to Angie Dodge's killer, but the reasons police honed in on him instead of any of his other relatives are detailed in the warrant. Remember, Chris Tapp told police a guy named "Mike" was involved in the murder. Police took to Facebook and found Usry's profile. Bingo. Facebook showed Usry had friends living in the Idaho Falls area. And then there's Usry's films.

The more Usry read, the more furious he grew that anyone would think he was a killer. But even more troubling was the idea that Angie Dodge's killer might be someone in his family.

Mike Usry Jr.: … just knowing that somebody in my family would — possibly do sumthin' like that is disturbing, I mean, to say the least, you know?

THE WRONG MAN

Michael Usry worried every day. He knew that Idaho Falls police suspected him of murdering Angie Dodge and the uncertainty of what would happen next kept him up at night until January 13, 2015 — more than a month later

Mike Usry Jr.: They sent me an e-mail … [reading the email] and it says, "Michael Usry Junior, we just wanted to let you know that your DNA did not match our crime scene DNA, something you already knew."

In an email from police, Michael Usry was officially cleared of the murder of Angie Dodge, but he was still thoroughly traumatized.

Anne-Marie Green: You were angry at Ancestry.

Mike Usry Jr.: I was angry at everybody … the police, scientists, you know, these database companies, you know … how could they misfire so bad?

"48 Hours" asked Ancestry.com about Usry's experience. In a statement a company spokesperson replied:

"Ancestry understands the responsibility that comes with the trust our customers place in us and protecting their privacy is among our highest priorities. Ancestry will not share any information with law enforcement unless compelled to by valid legal process, such as a court order or search warrant. The Usry case was unique. It involved a database we purchased that was an open and publicly available research resource at the time we bought it. After this case, we made the database private to help protect the privacy of our customers. This is also the only formal legal request for DNA related information we have received, as indicated in our transparency reports."

Mike Usry Jr.: You can't control fate and what happens to you. So, I just figured that this was — there was a reason for this, ah, happening.

Michael Usry decided he wanted to try and prevent it from happening to anyone else by making a documentary about his experience. He was shocked when Angie Dodge's mother was willing to talk. What he didn't realize is that Carol Dodge had an agenda of her own.

Mike Usry Jr.: She's fairly certain that a killer is in my bloodline.

Carol Dodge: I remember Mike and I sitting down … And I said, "OK Mike, here's a piece of paper. Now I want you to write down from your great grandfather to your grandfather to your dad … And he did me a genealogy sheet.

Mike Usry Jr.: My grandfather … had six other brothers. … Carol just wonders … "Hey, maybe it's somebody you don't even know. Maybe it's an illegitimate son of one of your Pappy's brothers."

Despite all that, Carol Dodge and Michael Usry have forged a rather odd close bond.

And after hearing Carol and Angie's story, the focus of Usry's documentary changed dramatically to Carol Dodge's search for her daughter's killer. He immersed himself in the case, starting with the man who had confessed: Chris Tapp.

DETECTIVE: How many times did he stab her before you let go? CHRIS TAPP: That first time?

Usry quickly learned that Chris Tapp was now claiming his confession was forced and the Idaho Innocence Project, headed by DNA expert Greg Hampikian, was now working to set Tapp free.

Anne-Marie Green: Based on the DNA, is there any way that Chris could've been in that room?

Greg Hampikian: No, not based on the DNA.

The more Carol Dodge learned about DNA, the more she questioned Tapp's confession: that he held Angie down while she was being stabbed.

Carol Dodge: It wasn't until I started studying science that I said, "It's impossible." … How could Chris admit in doing what he said he did, and there be no physical evidence?

But it wasn't just the science that bothered Carol Dodge. She believed that Chris Tapp's confession was coerced by the detectives who interrogated him:

DET. FUHRIMAN: Come on man, I mean, you're in the heat of the moment. She's putting up a fight. … You know, you're caught. You're right there in the middle.

Chris Tapp: I watch it and it's so frustrating.

"48 Hours" first met Chris Tapp when he was 40 years old. He'd been inmate number 56265 for 20 years.

Chris Tapp [to Anne-Marie Green]: You look at that 20-year-old kid, you know, and you realize, "God, I was just an idiot."

DETECTIVE: Think hard about it. I know it's — I know it's there …

Chris Tapp says his confession was a lie — a story fed to him by police and then forced back out of him on tape.

Chris Tapp: … you can see 'em specifically pointin' out facts to me. Or — or giving little innuendos.

DETECTIVE: This would be the stairs going up. CHRIS TAPP: OK. DETECTIVE: So, you went up these stairs.

Chris Tapp: … or hints of how the murder went down.

DETECTIVE: Well, this porch goes outside.

It all started because Chris Tapp's friend, a man named Ben who also knew Angie, was arrested in Ely, Nevada, for assaulting a woman at knifepoint. To investigators, the crime seemed similar to the attack on Angie, so while Ben was in custody in Nevada, investigators brought Chris Tapp in for questioning.

Chris Tapp says his confession was a lie — a story fed to him by police and then forced back out of him on tape. CBS News

Chris Tapp: Emphatically I said, "I had nothing to do with it. I don't know what you're talking about."

But instead of leaving it at that, Tapp, then just 20 years old, cooperated.

Chris Tapp: I felt like, trust 'em, they're not gonna do anything wrong.

Greg Hampikian | DNA expert: He doesn't know they can lie to him. … Most innocent people have no idea that the interrogators can lie to you.

First, Tapp was told there was irrefutable evidence that his friend Ben killed Angie, and that Tapp was there when it happened:

DETECTIVE: We're pretty sure we're — we know what happened and who did what and how, when, where and why …

Tapp kept denying all knowledge of the crime:

DETECTIVE: Did you hear her scream or anything like that? CHRIS TAPP: I wasn't there.

But detectives persisted, and even though he had a lawyer, Tapp kept talking.

Anne-Marie Green: And, so, when they offered you a polygraph, seemed like a good idea?

Chris Tapp: Yeah. Seemed like a great idea. I had nothin' to hide, no — no reason not to do it.

But Tapp was told he was being deceptive, and detectives promised him full immunity – no jail time — in exchange for the truth as long as he hadn't participated in the actual murder. That's when Tapp says he started telling police what he thought they wanted to hear:

DET. FUHRIMAN: Now are you sure Ben's there? CHRIS TAPP: Yes. DET. FUHRIMAN: You're — CHRIS TAPP: Positive? DET. FUHRIMAN: Yeah. CHRIS TAPP: Yes. DET. FUHRIMAN: OK.

Tapp told detectives he was there when Ben killed Angie Dodge:

DETECTIVE: You told him "don't do it, don't do it?" CHRIS TAPP: Yeah. DETECTIVE: OK, so did he — did he have the knife then? Pardon? CHRIS TAPP: Yeah.

But just hours later, detectives learned that Ben did not match the killer's DNA. A desperate Chris Tapp started changing his story, blaming several other friends for the murder.

Chris Tapp: I continued to lie, I continued to give 'em — story after story and it … They shoulda just stopped. But they didn't.

Anne-Marie Green: But Chris, why didn't you stop?

Chris Tapp: I didn't think I could.

When none of the men he named matched the DNA, Tapp says police still refused to let up. After 23 days and seven interrogations, Chris Tapp confessed to participating in Angie's murder and authorities voided his immunity agreement.

DETECTIVE: You're holding her down, OK. While she's being cut. DETECTIVE: You're holding her down, while she's being. CHRIS TAPP: Cut.

Chris Tapp: That's what was the end of it all. That's what brought me to prison.

Authorities have repeatedly dismissed Tapp's claims of a forced confession until an astonishing discovery would change the game. Never-before-seen videotapes of seven polygraph exams administered to Chris Tapp — tapes that convinced even Carol Dodge that Chris Tapp is innocent.

Carol Dodge: Chris Tapp basically just got railroaded.

Chris Tapp's new advocate



Carol Dodge took on a new mission to free the man convicted of her daughter's murder and find the killer who left his DNA — even if it turned out to be a member of Michael Usry's family.

ANATOMY OF A COERCED CONFESSION

Chris Tapp: You always gotta have a little faith. Gotta have a little hope. … And I haven't accepted this as my end.

Judge Michael Heavey: I can't imagine spending one day in prison, let alone 20 plus years.

Mike Heavey is a retired superior court judge who believes so strongly that Chris Tapp is innocent, he's spent the last four years trying to help prove it.

Judge Michael Heavey: When you look at the interrogation videos, he knows nothing.

DETECTIVE: So, Chris Tapp, Ben … Let it out. Let it out!

Judge Michael Heavey: He struggles for details.

DETECTIVE: You're there.

Judge Michael Heavey: Why? 'Cause he wasn't there.

Heavey runs a wrongful conviction project called "Judges for Justice," and took on Tapp's case after watching the interrogation tapes.

CHRIS TAPP [interrogation]: I wasn't scared. I wasn't even down the f---ing stairs. I wasn't nowhere around.

Judge Heavey became convinced that Chris Tapp had been coerced into changing his story an astounding six times and knew that something was missing.

Judge Michael Heavey: I was concerned. He went from one day saying….

CHRIS TAPP: [interrogation]: I wasn't there!

Judge Michael Heavey: … and the next day …

DETECTIVE: You're standing above her like this, like her head's right here. CHRIS TAPP: Yeah.

Judge Michael Heavey: "I'm at the crime scene and I stabbed her." I couldn't see how he made that jump. So, I went back to look at the polygraph. And my jaw just dropped.

CHRIS TAPP [polygraph]: Does it help to say that I'm nervous?

In between Chris Tapp's nine interrogations, detectives administered seven polygraph exams. All of them were recorded, but no one had ever bothered to look at the tapes because polygraphs are inadmissible in court and the sound is barely audible:

DETECTIVE: I have to advise you of your rights. CHRIS TAPP: OK.

Judge Michael Heavey: Polygraphs are typically used to assess the credibility of the witness, when they're done honestly.

Anne-Marie Green: And how was the polygraph used in this case?

Judge Michael Heavey: This case it was used to … trick Chris Tapp into giving false testimony … my polygraph expert says it was used like a psychological rubber hose … to get him to implicate himself in the murder of Angie Dodge.

Evolution of a confession

Judge Heavey says that detectives in this case broke the rules in the polygraph room and thought no one would ever notice.

Judge Michael Heavey: The United States Supreme Court has held … that it's improper to threaten. … you can't threaten because it leads to false confessions. … they threatened him with the gas chamber, being accessory to murder and being a conspirator to murder.

DETECTIVE [polygraph]: You know what accessory to murder is? TAPP: Yeah. DETECTIVE: That's being charged just like the person who did it; they get life in prison, gas chamber.

Judge Michael Heavey: They figured no one's gonna look at the polygraphs. So, it'll be hidden, no one will ever see it.

Heavey says Chris Tapp was brainwashed:

CHRIS TAPP [polygraph]: I'm scared. DETECTIVE: You're scared. And the reason why is because you – subconsciously you remember …

Judge Michael Heavey: Chris Tapp eventually comes to believe that the polygraph is an all-knowing scientific instrument that can read his subconscious and is telling the machine that he was at the crime.

DETECTIVE [polygraph]: Protect your own ass. …I wouldn't say this, but you're not a cold-blooded killer. You got trapped. CHRIS TAPP: [Takes a deep breath] Alright.

Judge Michael Heavey: Chris finally says, "Yes — I stabbed her because Ben threatened me." And then Chris said …

CHRIS TAPP: Did I do it?

Judge Michael Heavey: The police officer walks over and says, "Give me your hand." Like, he passed the polygraph.

Chris Tapp during a polygraph exam Michael Heavey

Judge Michael Heavey: And that gets Chris Tapp 30 years to life, charged with the death penalty. Ugly stuff.

Anne-Marie Green: Do you remember that moment?

Chris Tapp: Yeah [laughs]. Yeah. Scared. Scared. … That's pretty much the day my life ended.

But Tapp never told anyone about what happened during those polygraph exams.

Chris Tapp: I didn't know what they did in the polygraph tapes was wrong. I didn't know. … If I woulda known these things 20 years, 15, 10 years ago, then maybe we wouldn't be here today.

Idaho Falls police deny any wrongdoing in their interrogations or polygraph exams.

Anne-Marie Green: Do you think the polygraph was used as a coercive tool?

Chief Mark McBride: Well, I don't know that was the intent. I think the intent is find out the truth.

Over the years, the courts have upheld Tapp's confession as valid and admissible — and not the product of coercive police conduct.

Chief Mark McBride: I don't think they were tryin' to cause harm. … there wasn't any malicious intent, I don't think.

John Thomas: It's hard for me to wrap my head around what the police are thinking.

John Thomas is Chris Tapp's appellate attorney.

John Thomas: It's OK. You made a mistake. … Just say, "Hey, I made a mistake. We got the wrong guy. Let's all rally around and let's get the right guy."

Mike Heavey was hoping that the newly-discovered polygraph tapes would be enough for a judge to grant Chris Tapp a new trial.

Judge Michael Heavey: Those polygraph videos are now new evidence … They're the wedge to get Chris in front of a judge to see the coercion that went on.

Carol Dodge: I hope he walks out a free man.

Anne-Marie Green: It's not often you hear the mother of a victim say that about the only man serving time for her daughter's murder.

Carol Dodge: True.

FINALLY … A DNA MATCH

It was March 2017 and Chris Tapp was just two weeks away from two hearings that his lawyer John Thomas hoped would set him free.

John Thomas: We have too much evidence showing that Chris Tapp wasn't there.

Anne-Marie Green: Have you ever found DNA that matched Chris Tapp at the scene?

Chief Mark McBride: No.

But Police Chief Mark McBride maintained that given Tapp's confession, the absence of his DNA at the crime scene proved nothing. Then, in a stunning turn of events, the district attorney's office wanted to make a deal. Tapp's murder conviction would stand, but the rape conviction would go away, and there would be no probation.

John Thomas: Chris Tapp would just take his lumps on his 20 years and – and walk a free man.

Tapp took the deal. That was in 2017. Two years later ...

Chris Tapp: I've got a full-time job. I'm married. I've actually … become that productive member of society that I truly thought I could become.

Angie Dodge, 18, was murdered in the summer of 1996 Carol Dodge

Meanwhile, Carol Dodge never stopped hunting for Angie's killer.

Carol Dodge: I've done a lot of research on technology. … and I was bound determined I was going to solve my daughter's case.

Not long after Tapp's release, Carol Dodge got some help. New Police Chief Bryce Johnson says he already had his sights set on Angie's case.

Chief Bryce Johnson: I talked to all the detectives. And I kind of told them … "let's not worry about what's been done over the past 23 years. … We have one mission. It's to find out who left this DNA sample."

It wasn't easy, but two years later there was news. On May 16, 2019, Chief Johnson told the world they had finally found and arrested the man who matched the DNA.

CHIEF BRYCE JOHNSON [to reporters]: Carol inspired us all to try harder and to do better.

Chief Bryce Johnson: The thing about Carol is she knew more about DNA than I knew about DNA.

What Carol Dodge knew is that CeCe Moore and a company called Parabon NanoLabs had been making huge strides in solving cold cases using genealogy and public databases.

CECE MOORE [to reporters]: This is our 56th case this year at Parabon using genetic genealogy to identify unknown suspects and victims.

Moore and Parabon were able to generate an even more complete DNA profile of Angie's killer than ever before. That profile could now be uploaded to a large public DNA database called GEDmatch — a free website that allows people to upload their own DNA profiles in search of relatives. In return, if users opt in, their data can be accessed by law enforcement.

CECE MOORE [to reporters]: When we upload that data, we get a list of people that share significant amounts of DNA with the unknown suspect.

Moore found a family tree that she was confident contained a killer, and it was Michael Usry's family tree.

Mike Usry Jr.: He apparently was a split off of the Usry family from something like over 100 years ago.

Anne-Marie Green: So, we're talking about the right family tree, but the branch is way all off on the other side.

Mike Usry Jr.: Way off. Yeah.

Anne-Marie Green: Did you know anything about this … offshoot of your family?

Mike Usry Jr.: No. Totally not.

Now Detective Sage Albright and Captain Bill Squires were laser focused on the men in this way off branch of Usry's family tree.

Captain Bill Squires: It had been whittled down to a list of persons, that I think was around 10 or 11 people that we were able to reduce down further just because they weren't in Idaho at the time … Or they were 3 years old at the time.

Left with a list of six possible suspects, detectives had to secretly collect their DNA — following them around for days, waiting for discarded cigarette butts, soda cans or plastic straws. One guy was a tobacco chewer.

How police collected a suspected killer’s D...

Chief Bryce Johnson: The detectives came out, kind of scooped that up. … We sent it off to the lab, came back negative. It wasn't the person we're looking for.

Then they started running out of men and a fear set it in.

Chief Bryce Johnson: The thing we were concerned about was … Is there a child out there that nobody knows about, right? Did someone have a baby and it's not in the genealogy record?

They were right. An obituary miraculously led CeCe Moore to a missing Usry. Helen Darnell had a daughter who was once married to an Usry. After their divorce, a son was born under a different last name: Brian Dripps.

Chief Bryce Johnson: When we looked at that name … we realized we had talked to him in the first days of the investigation. He lived across the street from Angie.

Carol Dodge [emotional]: I literally said, "you've got to be kidding." Brian Dripps … He was right across the street. … it took me 23 years when they had it in the first 25 pages of the investigation.

The police report indicates that the day of Angie's murder, a young police officer who was canvassing the neighborhood had briefly questioned a then- 31-year-old Brian Dripps.

Chief Bryce Johnson: Everyone in that neighborhood got — got a knock on the door.

Brian Dripps was living across the street from Angie Dodge at the time of her murder. KDIK

Dripps denied any knowledge of the crime and police never asked for his DNA. About seven weeks after the murder, Dripps left Idaho Falls. He was living in Idaho, about 300 miles away, when a cigarette butt linked his DNA to the crime, and detectives picked him up for questioning.

Det. Sage Albright: It was obvious he was nervous. He put on a pretty good game face, but his — his hands started to shake.

For several hours, Dripps denied any involvement in Angie's death.

Det. Sage Albright: And when we told him "we have your DNA at the crime scene" he — there was a noticeable change in his demeanor … And eventually he told us that he had been involved.

Detective Albright says Dripps also reported that he acted alone.

That meant Chris Tapp could not have been there. Two months after Dripps was arrested, Tapp was back in court — this time, to be fully exonerated.

DANIEL CLARK | PROSECUTING ATTORNEY [In court]: There's clear and convincing evidence the defendant was convicted of a crime for which he did not commit.

Carol Dodge congratulates Chris Tapp after he was fully exonerated. KDIK

This case is the world's first exoneration by way of genealogical DNA testing.

Mike Usry Jr.: I'm extremely happy for him. … I hope that he can, piece together his life again.

But Usry says he still has his doubts about the use of genealogy.

Mike Usry Jr.: Kind of a scary thing to me, to think about what this world is going to be like if all of our genetic codes are in a computer database. Once it's in a computer, that's almost like more permanent than carving something in stone nowadays. … But, I think that we really, really need to be cautious and take a step back and look at this technology.

Carol Dodge disagrees.

Carol Dodge: Without technology, without genealogy research, we would have never found Angie's killer.

Carol Dodge: It is the key that opens the door to justice.

Brian Dripps has pleaded not guilty and is in custody awaiting trial.

"5 FOR HOPE"

Carol Dodge and her son Brent have started the nonprofit "5 For HOPE" to raise money for underfunded cold case foundations and police departments.