Tennessee man convicted of trying to kill girlfriend after wife mysteriously disappears in another state

Young mother Shelley Mook dropped off her daughter at her ex-husband's house in Shelbyville, Tenn., on Feb. 28, 2011, and was never seen again.

Brittany Brooks remembers well the day when she and her best friend Shelley first met Tyler Mook in Pennsylvania. Not long after that, 18-year-old Shelley and Tyler, six years older, are married with a baby on the way, headed to Tennessee to live near his family. Shelley gives birth to a little girl named Lilliana.

But stress on the young marriage proves to be too much. After six years together the couple divorces. Shelley moves into an apartment in a neighboring town and starts work as teacher at the local middle school. She is sharing custody of her daughter with ex-husband Tyler when she starts dating someone new.

Things are looking up for Shelley. Until the day she makes an appointment with a man at her apartment to get some work done. But the handyman there said Shelley never showed up. The next day, Shelley does not go to work.

Brittany Brooks starts making calls.

Shelley's ex-husband Tyler also calls police after she doesn't show up to pick up their daughter at his house.

At around the same time, firefighters in a neighboring county are busy cleaning up after a late night car fire in a remote field. Nobody is in the vehicle, and authorities figure it's likely an insurance job or a stolen car.

"They did find an accelerant, so they knew this was arson," said journalist Traciy Curry-Reyes, who covered the case. "They knew it was set but they didn't know why. They thought this was probably somebody joyriding and they dumped the car."

Everything in the car goes up in smoke. Authorities trace the vehicle identification number back to Shelley Mook. And Shelley, 24, is nowhere to be found.

Police start retracing Shelley's steps from when she was last seen leaving work headed home to meet with a man working on her apartment. Police interview the handyman and clear him.

Shelley's family and friends started to panic when her credit cards, cellphone and bank accounts all went silent.

"Never, never would she ever leave her daughter. He daughter is her world," said Shelley's friend Brittany Brooks. "She did not leave voluntarily."

The Tennessee Bureau of Investigation has now been called in to re-examine the case, meticulously looking into all possible suspects including the handyman she was supposed to meet at her apartment, and her new boyfriend. His alibi was easily verifiable, according to private investigator Kevin Keele, who was hired by Shelley's family to help find her.

Keele says once cops cleared the handyman and the new boyfriend, they shifted their focus back on her ex-husband, Tyler Mook. And it turns out that things in the marriage were a lot tougher than many people realized.

"He was abusive, at times cruel," said journalist Traciy Curry-Reyes. "Court records show that he pushed her around, snatched her around when he would get upset. There is a record of the domestic violence that was going on in that house, and that was distressing to her."

Tyler says he called the cops the day Shelley went missing, saying she was supposed to pick up their daughter, but she never showed. Now police believe Tyler may have been the last one to see Shelley. In fact, they say she actually stopped at his house with their daughter Lilliana in her car.

"After getting out of school and picking up her daughter, she came to Tyler's residence that afternoon, supposedly to return a box of Tyler's belongings," said Keele.

As Shelley's family's suspicions mount around Tyler, Shelley's mother files for custody of 6-year-old Lilliana.

Tyler fights to keep her, and is interviewed on camera during a video-taped custody hearing. But once on the hot seat, he clams up.

"Shelley's family took him to court because they thought once they took him to family court, he would answer some questions, but they were wrong," said Keele.

Tyler Mook pleads the Fifth Amendment more than 150 times. He does say he had sex with Shelley in his house on the day she went missing. But he declines to elaborate and takes the Fifth Amendment again.

Now authorities interview little Lilliana about the day her mother disappeared, and her answers raise a huge red flag.

"The version Lilliana told early on, Shelley got out of the car, went to the door, left her in the car seat," said private investigator Kevin Keele. "Shelley went inside with Tyler. At some point Tyler came back outside, got her out of her car seat, took her to her old bedroom. She said she never saw her mother when she came into the residence, into the bedroom."

Police name Tyler Mook as a person of interest in Shelley Mook's disappearance But they declined to talk about the case with Crime Watch Daily.

Private investigator Keele has also spent countless hours digging for facts and working closely with Shelley's family and the law.

Ten days after Shelley's disappearance, Keele also finds what may yet turn out as a key piece of evidence: a surveillance tape from the early morning hours after she went missing.

"I was able to uncover from a convenience store several miles from his home that night, pulling up in his red S-10 truck," said Keele. "It does stop at the Dumpster for roughly five to 10 minutes. The Tennessee Bureau of Investigation has custody of that video."

Keele says they haven't told him anything about that video.

Meanwhile, investigators in the custody case are floored by another shocking revelation involving Lilliana.

"They found out that Tyler had been talking to his 6-year-old about burning down, down his ex-mother-in-law's house. That was unimaginable. He wanted to give the little girl matches so she could actually help burn down her grandmother's house."

Ultimately Shelley's family wins custody of Lilliana, but Tyler is still seemingly obsessed with getting her back.

Evidence in a 911 call he made by mistake. Tyler apparently "pocket-dialed" 911. The 22-minute conversation was recorded. In it, Tyler Mook talks to his father while they work with power tools. Most of it is garbled. But what comes through seems to be about Shelley's missing-persons case.

"They know that I'm not going anywhere right now because I don't have Lilli," Tyler can be heard saying. "They can't prove nothing. They wanna come and arrest me with a warrant."

And he talks about a car -- exactly whose car we don't know.

"Something keeps bothering me about that car. And they're gonna try to bust me with that," Tyler says on the recording.

Minutes later a second call to 911 comes in from a very concerned Tyler Mook. This is one he intended to make.

Tyler Mook has never been charged with Shelley Mook's disappearance, and his lawyer has denied he had anything to do with it. But Tyler's troubles with the law are far from over.

Tyler Mook says he had nothing to do with the disappearance of his ex-wife. Police say he's definitely a person of interest. Tyler is about to have more problems than just answering questions about his ex.

Tyler Mook moved to Florida, looking to start a new life. He buys a fast boat and has a hot new girlfriend, 25-year-old Robin Doneth, who also has a young daughter.

Robin says she didn't know anything about Tyler Mook's past in Tennessee. For a while she didn't even know his real name.

"I saw a name on the side of his boat, 'Mook Racing,' and I asked him what that meant, and he said 'That's my last name,' and I said 'I thought you said your last name was Cook.' And he said, 'No, I was just joking. It's Mook.'"

But Robin isn't laughing. She searches Tyler Mook online. And her eyes are opened. She didn't know what to do. She talked to her mother, who told her to get away from him.

Robin lets Tyler Mook know what she knows. But he wants to explain. She agrees to meet him at a local bar. He tells her not to believe it, tells her none of it is true. She tells Crime Watch Daily she wanted to believe him, that he was a smooth talker.

She continued dating Tyler, thinking her relationship was heading toward marriage, right up until the day Robin joins Tyler along with his brother Andrew and his girlfriend for a cruise on his speedboat. That's when, Robin says, she wished she had listened to her mother.

"When I got on the boat I had noticed that there was definitely alcohol-drinking the whole day," said Robin.

Robin says Tyler is angry at her for being late and guns the boat to full throttle.

"I said if you hit a sandbar you're gonna kill us all. And I just kept yelling at him to slow down, slow down," said Robin. "And then I guess he finally had enough." And for the first time, she meets a Tyler Mook that she never knew existed.

"He shut the motor off, and then he grabbed the sunglasses off my head," said Robin. "I was trying to call my mom and he grabbed my phone and threw it under the cabin. And he threw me over the boat into the water."

But it's not over.

"I thought he was just joking, and then I felt him jump in behind me," said Robin. "And then he grabbed me and turned me around and held me under, upside down."

And now, Robin says, it becomes a desperate battle for survival against an enraged Tyler Mook.

It happens so fast that Tyler's brother Andrew and his girlfriend on other end of the boat are hardly aware of the danger Robin is in at this moment.

"I was just pleading with him to please let me go, he came after me again, that's when I yelled 'Andrew, please help me,' and then he pushed me under again," said Robin.

Robin says she is forever thankful that Andrew Mook took action, claiming he jumped in the water, put Tyler in a headlock and got him off of her and back on the boat.

"I just knew I had to get away from his boat as fast as I could. And then I saw a boat coming from the other way and I just pleaded and begged him to just please get me out of the water. He just tried to kill me," said Robin.

The second boat takes Robin to shore, and soon after that she reports the attack to police. Tyler Mook is charged with battery

And then, days after the incident on the boat, a blast from Tyler's past: Robin says detectives from Tennessee show up in Florida, and they met. We don't know exactly what was said in that meeting. But shortly afterward, the battery charges against Mook are dramatically escalated to attempted murder in the first degree.

Assistant Florida State Attorney Kristen Chase says Tyler Mook's attack against Robin Doneth is clearly premeditated.

"We can't bring any part of that Tennessee case into our Florida case," said Chase. "It didn't factor into our decision because it couldn't. We only looked at the facts in Florida and the facts in Florida supported it being filed as an attempted murder case."

But getting a conviction in court could be a challenge. In the past Mook's family has been solidly in his corner. Now, the prosecution needs his brother Andrew to open up about what happened on that boat.

"He didn't want to testify, we didn't force him to testify," said Chase. "He was getting a lot of pressure from his family not to."

The trial gets underway as Robin takes the stand. Then it's Andrew Mook's turn. And it's make or break time for the prosecution.

"She yelled for me," Andrew testified. "Yelling when she came up, 'He's trying to kill me.'"

Kristen Chase is grateful for the testimony. And she knows it wasn't easy for Andrew.

"He said the person that he was most responsible to was first God and then his son," said Chase. "He said at the end of the day he loves his brother but he has to tell the truth."

Tyler Mook did not testify during the trial. The jury's verdict: Guilty on the lesser charge of attempted second-degree murder. It's not what Chase was looking for, but she'll take it.

"Because the relationship was seemingly fine before this to them it seemed more of an attempted second-degree murder, something that wasn't premeditated," said Chase.

Tyler Mook was sentenced to 12 years in prison.

And that's good news for Robin Doneth, for now. She's not the only one who is glad that Tyler Mook is off the streets.

Attending the trial is an out-of-town guest that hangs on every word: Shelley Mook's mother, who was there for Robin.

Tyler Mook has never been charged in connection with Shelley Mook's disappearance.

But back home in Tennessee, her best friend Brittany Brooks hopes that justice will one day prevail for Shelley.

While Tyler Mook sits in prison, the search for what really happened to Shelley continues.