Alexis Murphy remains missing after she disappeared in August 2013.

She went on Twitter to tell her friends she was off on a road trip. But somewhere along the way, Murphy vanished. Who's responsible?

Police make an arrest, but do they have the right man?

Senior pictures are right around the corner for 17-year-old Alexis Murphy, and she is headed out to get her hair done.

"I was getting up to go to work. I knew I was supposed to give her some money for her hair," said Laura Murphy, Alexis' mother. "She was laughing, she was happy. And she walked out the house and that was the last time I ever seen her."

Just after 3 p.m., Alexis posts on her Twitter account: "burg bound!" She's on her way to Lynchburg, about a 20-minute drive from her home in Shipman, Virginia.

Alexis' mother is on her way out too, to work the overnight shift at the post office.

But in the wee hours of Sunday morning, Alexis' grandmother, who lives with them, wakes to find Alexis didn't make her midnight curfew.

"She had never done that before, that's something that's not right," said Laura Murphy. "That's not Alexis."

"Laura called me and she said Alexis didn't come home, and I told her right then and there she needed to call the cops," said Troy Brown, Alexis' father. "I was trying to keep calm and not panic, because, you know, as a father in this situation, by not coming home at her curfew and not bringing my car home, just about anything runs through your mind."

The local sheriff's department is notified of the missing teen, and so are friends of Alexis, and she has many. Alexis' social media footprint is large, with thousands of followers-turned-searchers.

"Social media was a big help because they put it out there so people just start coming and searching with them, but they called the state police in and they had the helicopter in the air that night, the FBI was on ground too," said Laura Murphy.

Then just three days after Alexis disappears, police make a disturbing discovery.

"Her father's car that she was diving was found in a movie theater parking lot here in Charlottesville, abandoned, nobody was in it," said Anthony Martin, former Nelson County Commonwealth Attorney.

But at some point, someone was, and it's captured on nearby mall surveillance cameras.

"The car is seen pulling in around 10:30 at night the day after she went missing," said Martin. "You couldn't see who got out of it though. They really tried to enhance the video. But it was just a very grainy black-and-white surveillance video. It was at night. We were never able to see on the camera who drove the car."

Then investigators get a hunch.

"It was more or less just brainstorming where she could possibly go. We knew that was a place she would hang out," said Martin.

The Liberty gas station in Lovingston, where local teens hang out after school and on weekends.

"We did find video of her coming into the gas station and purchasing gas shortly before she disappeared," said Martin. "It was absolutely normal. She seemed to be happy, there was nothing wrong, she didn't seem upset."

But on her way out of the gas station, frame by frame, there it is:

"A man holding a door for a woman to leave the store and she walks out, doesn't look at him, doesn't say anything, she doesn't stop, just an everyday, nothing extraordinary about it," said Martin.

The man in the surveillance video holding the door for Alexis is sporting a large, unique neck tattoo. Cops take notice. And they take note of the man's distinctive vehicle, a camouflage Chevrolet Suburban.

At the same time, the FBI zeroes in on Alexis' cellphone signal: it's pinging and it's eerily close.

"We determined that her cellphone was located in an area about maybe one mile north of that gas station," said Anthony Martin.

When FBI agents and Virginia State Police swarm the area of the cellphone's location:

"It was an abandoned property," said Martin. "It was an old house right beside Route 29 right along the main highway. Of course since it was the summertime there was so much vegetation, five feet away from the road, you're in the shadows."

And parked within the overgrown brush was a camouflage Chevy Suburban.

Quickly, detectives are greeted by a familiar face.

"He had a very large tattoo on his neck of Daffy Duck," said Martin.

Investigators believe he's the same man on the surveillance tape at the gas station who held the door for Alexis.

"He met them at the beginning of the property and he certainly didn't say anything directly that would implicate him," said Martin.

But the creep factor is about to go off the charts when seasoned detectives approach his camper.

"He had a video camera on top of his camper pointing out to the driveway, and just his general demeanor, he was normal at first, he's the kind of person that makes the hair on your neck stand up, I guess is the best way I can put it," said Martin.

The man identifies himself as Randy Taylor, and invites detectives inside. Once inside the camper, something sparkly catches a detective's eye.

"A diamond stud, which would be similar to a nose piercing or an earring, in the carpet, as well as a fingernail. On the pillow of his bed there was a long black hair that was consistent with an African-American female," said Martin.

But they still need more. Police leave Taylor's property and take the potential evidence for DNA testing.

Upon further review of gas station surveillance video, they concentrate on another angle focused outside the gas station.

"Shortly after she was seen leaving the store with him holding the door, you could see his vehicle go by, northbound, which is where his camper was, and then her father's Nissan right behind him," said Martin.

The potential evidence police discovered inside Taylor's camper is sent to the Virginia State Police crime lab for DNA testing. The diamond stud, strand of hair and broken fingernail matched Alexis' DNA.

"Once that was a match, he became a clear suspect then," said former Nelson County Commonwealth Attorney Anthony Martin. "Once he knew that we knew, he finally said 'OK, I saw her.'"

"He said that her, and as he put it, 'a black guy with dreadlocks,' came to his camper to get drugs," said Martin. "They drank a few beers and then she left his camper, as he put it, 'laughing and smiling,' and that was the last he saw of her."

Randy Taylor gives cops a name.

"His name was Damien Bradley, and Mr. Bradley, he knew of Alexis," said Martin. "We go and talk to him because we want to get to the bottom of this. He flat-out denies even ever meeting Mr. Taylor. He certainly wasn't the last person to be with Alexis. He didn't accompany her to Randy's camper."

And according to detectives, Damien Bradley's alibi is solid: he was with his father in Alabama during the weekend of Alexis' disappearance.

With potentially incriminating DNA and Randy Taylor's false statements, cops have enough to arrest him on abduction charges. When police tell Alexis' family they've made an arrest, the name Randy Taylor doesn't ring a bell, but his face does.

"When I saw his face I thought, you know, 'This guy looks really familiar,' but I couldn't put my finger on it until it came out that he used to work at a used car lot, and I had actually bought a used car from them, and he was the person who handed me my keys," said Trina Murphy, Alexis' aunt.

But who is Randy Taylor? When detectives start asking around the small town, they get an earful.

"The attendants at the gas station where they were seen together, they just said he always made them feel uncomfortable," said Anthony Martin. "He would just take his Suburban back into a corner parking lot and just sit there for over an hour and just watch people coming in and out of the store."

Cops get a call from an employee at a porn shop who claims just 45 minutes before Taylor was at the gas station, he was in his store purchasing two adult videos.

"We felt that there was a sexual motivation to this," said Martin. "It was at that point that we felt that we really needed to get inside the camper and we started developing probable cause to get a search warrant."

They get one, and federal agents and local police officer race to Taylor's property to take another look inside the camper. And under the couch they make a dreadful discovery.

"They found a T-shirt balled up under the sofa, and it had black hair extensions, and then a set of artificial eyelashes," said Martin.

The shirt appears to be the same one Taylor is wearing in the surveillance video on the day of Alexis' disappearance -- expect for one notable change.

"There was a stain on the back of the shirt," said Martin. "It turned out that it was blood. The DNA on the eyelashes, the hair extensions and the bloodstain matched Alexis' DNA."

Inside the abandoned home on Taylor's property, investigators find a scrapbook with pornographic pictures, with the faces cut out, and photos of a female were taped on top of those photos, according to Martin. The female is the daughter of one of his coworkers.

Alexis' cellphone is still missing. Her friends and family claim the social media maven was never without it.

"The Department of Corrections in Virginia has K-9s that are specifically trained to detect cellular phones," said Martin.

Police K-9s are unleashed on Taylor's property and find Alexis' shattered iPhone about 15 feet from Taylor's camper.

With the evidence mounting against Taylor, he sits in a jail cell on abduction charges.

At the same time, there are numerous police reports of other girls who have gone missing in the same area of the town of Charlottesville.

With the increasing number of missing girls in the area, authorities wonder if they have the right man, or if a serial killer is to blame.

October 17, 2009: Virginia Tech student Morgan Harrington, 20, goes missing from Charlottesville, the same town where Alexis' car was discovered. Morgan's body was found three months later in a field south of town.

September 13, 2010: Samantha Clarke, 19, went missing in the town of Orange, Virginia, just minutes from Charlottesville. Her body was never found.

September 13, 2014: Hannah Graham, 18, disappeared after a night out with college friends in Charlottesville. Five weeks later her remains were discovered in a nearby abandoned property.

For five long months, authorities searched for Alexis Murphy.

"At that point, I started researching homicides without a body, and I ran across a case in Virginia from the 1980s, the Stephen Epperly case," said Anthony Martin. "That woman has not been found in over 30 years. Her killer has been convicted and he's in Department of Corrections."

In an unprecedented move, Prosecutor Anthony Martin charges Randy Taylor with Alexis Murphy's murder.

"We should not reward a person by not charging them with murder just because they are good at hiding the body," said Martin.

Only two cases in Virginia have ever moved forward with a murder charge without a body. But after only five days of testimony, the jury of five men and seven woman found Randy Taylor guilty of first-degree murder and abduction with intent to defile. He's sentenced to two life sentences.

Then in a stunning turn of events, just two months after Randy Taylor's murder conviction, a bombshell: A suspected serial killer makes local news headlines -- Jesse Matthew.

"He was a person of interest that came about in the Morgan Harrington case, and then he later came up with the UVA student Hannah Graham," said Martin.

Jesse Matthew is charged with the abduction and murder of Morgan Harrington and Hannah Graham. Both girls went missing out of Charlottesville, the same area where Alexis disappeared.

"He was a large African-American guy, a black guy with dreadlocks," said Martin. The same description Randy Taylor gave cops of the man he claimed left his camper with Alexis Murphy the day she disappeared.

Authorities begin to wonder if they've just convicted the wrong man. Randy Taylor sits behind bars convicted of abducting and murdering 17-year-old Alexis Murphy. Taylor has always maintained his innocence and sticks to his story.

"Jesse Matthew was a person of interest in two other homicides in Central Virginia, and because he would sort of fit the description of what Mr. Taylor said, his attorney wanted us to explore whether or not Jesse Matthew had anything to do with Alexis Murphy," said Anthony Martin.

Cops take Matthew's DNA and compare it to other samples extracted from Taylor's camper.

"He was excluded from our case. We strongly feel he had nothing to do with Alexis' case whatsoever," said Martin. It's proof that Randy Taylor is the killer and his murder conviction and two life sentences will stand.

But now with hard DNA evidence, Taylor changes his story. He makes an 11th-hour confession, and wants to cut a new deal.

"He suddenly, at sentencing, wants to give us the location -- or as he put it, 'Tell you where she is,'" said Martin.

Randy Taylor tells prosecutors that he will tell them where Alexis' body is in exchange for reducing his two life sentences down to 20 years.

Alexis' family is quick to react.

"I couldn't rest or my family couldn't rest knowing that we didn't do all that we could when we had the opportunity to put this monster away forever," said Angela Murphy, one of Alexis' aunts.

That means no deal for Taylor. Sadly, it also means no real closure for Alexis Murphy's family.

"She deserves to be laid to rest somewhere where we can go, you know that's her place," said Trina Murphy, Alexis' aunt. "She deserves that. Everyone deserves that."

"We'll keep looking and hopefully find her, but we're not going to give in to him," said Anthony Martin.

"I definitely think if he didn't get the two life sentences, that he would have struck again," said Angela Murphy.

Or did he already?

"Randy Taylor has done this before with the case in Orange County," Martin said. "He has not been charged yet. That's still an active investigation."

Her name is Samantha Clarke. The 19-year-old went missing from the town of Orange, just 28 miles from Charlottesville, in 2010. She has never been found.

Cops originally suspected Jesse Matthew. Clarke's case was reviewed to see if there was any connection. There wasn't, at least not to Jesse Matthew.

"[Randy Taylor] was the last person that tried to contact Samantha Clarke before she went missing, and she's never been seen again," said Martin.

"I don't think Alexis was his first rodeo. I don't think she was the first girl," said Trina Murphy. "I don't think he ever imagined that the FBI would be involved or that this case would ever be as big as it has become. And that's where he made his mistake."

A mistake that suggests that Jesse Matthew isn't the only suspected serial killer in the small community of Charlottesville, Virginia.

According to investigators, Randy Taylor knew Samantha Clarke because they lived in the same trailer park at the time of her disappearance.

Orange Police Chief Jim Fenwick confirms that Taylor spoke to Clarke on the phone immediately before she went missing.

Fenwick told a local newspaper: "We've heard through various means that the Samantha Clarke case is being referred to as a cold case, and quite frankly, that's the furthest thing from the truth."

The chief says Randy Taylor is currently a person of interest in the Samantha Clarke case. If convicted of Samantha Clarke's murder, Randy Taylor could face the death penalty.

"Randy Taylor will never be out of prison to exact this kind of pain on someone else, but please believe there are plenty more out there like him," said Trina Murphy.

Jesse Matthew has now been convicted of abducting and murdering Morgan Harrington and Hannah Graham and is serving four consecutive life sentences.

As a result of the three murders, Alexis' Aunt Trina is now working with an organization called Help Save The Next Girl, by remembering the three they lost.