In Green Bay, Wisconsin, police have just named a prime suspect in the mysterious disappearance of missing college student Amber Wilde.

Steve Wilde raised Amber and her little sister as a single dad. The conscientious little Amber grew into a young woman with big dreams. Amber is well on her way as a junior at the University Of Wisconsin -Green Bay.

Amber chronicled every detail of her journey in her diary, writing down daily activities, who she spoke to, and even her most private secrets. Just hours after one of her final entries into her diary, Amber is in a car crash while on her way to class.

"She had rear-ended another car. She had made contact with that driver, they agreed to exchange names and speak later in the day," said Green Bay Police Detective Lee Kingston.

There was minimal damage, but Amber did smack her head on the windshield.

"She went and saw the medical staff at school. They told her that she most likely had a concussion and that someone should check in on her whether it be in person or with phone calls," said Det. Kingston.

Steve Wilde talks to his daughter throughout the day. Amber tells her dad she's got a blinding headache and asks him to call in the morning to make sure she wakes up for class.

"When it went 12 hours from our last conversation I knew something wasn't right," said Steve. "I had a key to her apartment so I was able to go in there and there was nothing going on in that apartment. Nothing really jumped out and said 'This is what happened,' or pointed me in a direction as to where she was."

When the worried father notice's Amber's car's missing, he immediately calls Green Bay Police.

"It was just totally out of character for her to go missing on her own, so there was a good concern early on that someone else most likely was responsible for her disappearance," said Det. Kingston.

Then cops discover their first clue: Days after Amber went missing her car was found across the street from where the Green Bay Packers play Lambeau Field. But Amber is nowhere to be found.

"Her car was found unlocked," said Green Bay Police Det. David Graf. "The keys were in the car, her purse was located in the trunk of the car, and her phone was actually located on the front seat of the car, still plugged in to the cigarette lighter."

And no one saw who drove the vehicle outside the bar. Could Amber have amnesia from the concussion and simply wandered off? Possibly.

But when Steve Wilde sees the inside of his daughter's car, he knows his little girl is in big trouble.

"She had very short legs and the seat was always up under the steering wheel," said Steve. "When they found the car, the seat was all the way back."

"Could be one of two things: Someone either did it intentionally to throw us off, or someone very tall was the last person to drive the car," said Det. Kingston.

There's something else eating away at this worried dad. Just two days before Amber went missing, she had her car serviced, and they wrote down the mileage on her odometer. When Amber's car is found at Lambeau Field, Steve notices about 900 new unexplained miles.

Police begin to suspect the absolute worst has happened to Amber.

"We've pretty much ruled it a homicide. There's nothing that we can find or have been able to find that she went missing on her own," said Kingston.

So who would want to hurt Amber?

Then police get their biggest clue from Amber Wilde, in her own written words.

"She's her own star witness," said Detective Graf.

Cops find her personal diary. And there in black and white cops find the words that spell out a possible motive: "I'm pregnant."

"I was the first one that she told that she was pregnant," said Laurie Ehnert, Amber's aunt.

Amber confides in her Aunt Laurie, then tells the rest of her family it's an accidental pregnancy, but that she plans to keep the baby.

"It surprised me, but if was going to happen to anybody, I felt she was the one person who could overcome this," said Amber's father Steve Wilde.

Amber continues her pre-med studies at the University of Wisconsin-Green Bay, and begins planning for the arrival of her bundle of joy.

"Everybody was supportive. She really didn't have anybody that wasn't supportive," said Laurie Ehnert.

Except possibly one person: The man Amber claims is her baby's daddy, Matt Schneider. Ehnert says Amber did tell him about the pregnancy, and says Schneider was not happy about it.

Amber tells Laurie the father is a burly 6'5" 21-year-old highway construction worker she met at a party named Matthew Schneider.

"Of course she was upset with that, but she just wanted the baby to know his or her father and have him be a part of that child's life," said Laurie.

According to Laurie, Amber tried relentlessly to get Schneider involved with her pregnancy, but he refused. Laurie claims Matthew even asks Amber to get rid of the baby.

"He wanted her to have an abortion. He didn't want anything to do with it," said Laurie. "She told me she never would do that."

Green Bay Police begin digging deeper into Amber's secret diary, and in her own words she gives cops alarming insight into her final conversations with Schneider.

"Matt basically was giving her ultimatums or threatening to either harm himself or that she'd never see the kid again, and he made these type of statements," said Det. Graf.

Would not wanting a baby be a motive for possibly murdering Amber? On its own, maybe not. But Schneider has other serious issues. Cops find out he's also got a fiancée.

"I think the biggest thing was he didn't want his fiancée to know because he didn't want that relationship to end," said Det. Kingston.

Cops say in her diary Amber makes it clear she wants Schneider to come clean with his fiancée about the baby. But when he refuses, Amber confronts Schneider's fiancée face to face.

"She did tell Matt's fiancée that she was pregnant with Matt's baby and she also wrote a letter to Matt's mother," said Kingston.

According to Amber's diary, Schneider was livid.

"The only thing she had mentioned one time was that he was mean to her," said Laurie Ehnert. "I said what do you mean? Does he hit you? She said 'No, no, no, always cutting me down, telling me I'm fat and telling me I'm ugly' or whatever. I said if he would ever do anything to hurt you, you get away from him."

Green Bay Police say looking back at Amber's diary they now believe she was leaving them clues.

"It's her talking to us. It's her telling us what was going on in her life and what she was doing," said Det. Kingston.

So they hunt down Matt Schneider to get his side of the story. And it's not at all what they expect to hear.

"He denied to the initial detectives ever having a sexual relationship with Amber," said Kingston.

Schneider tells investigators he met Amber at a local restaurant and barely knew her.

"He told a detective that he probably maybe talked to her twice," said Det. Graf.

Schneider's fiancée tells cops Amber had an almost fatal attraction to Matthew, and was making it all up.

"She states that Matt in no way had any sexual contact with Amber at all, and the fact that Amber was just infatuated with Matt and harassing him," said Det. Graf.

Was Amber just a confused teenager desperate for attention? Police believe that secret diary could hold the key to who's lying.

Green Bay Police have not released Amber's diary as part of their ongoing investigation, but they did allow me to read several of her entries about her relationship with Matthew Schneider. She was very graphic about their sexual relationship. And what I read made it very clear that this was no one night stand. In the diary she even wrote about different sexual positions.

Family members told us their relationship was hot and heavy for four months, then went ice-cold when he found out Amber was pregnant.

Crime Watch Daily has also confirmed a doctor preformed an ultrasound and determined Amber was about four and a half months along at the time of her disappearance.

Matt Schneider maintains he did not have sex with Amber and the baby was not his. If that's true, and he only talked to Amber a couple of times, cops want to know how Schneider can explain a key piece of the mystery: his phone records.

"Between the time period they first met to the time period she went missing, from phone records and other statements, maybe around 60 times for sure," said Det. Graf. "There clearly was a back-and-forth going on documented very well through phone records and a diary that Amber kept."

Cops were able to cross-reference the dates and times with Amber's diary and phone records to determine the content of each call.

"Most of the conversations, to our knowledge, were about Amber being pregnant, and then once she was missing, there was never phone contact since," said Det. Graf.

Police are now saying those phone records constitute evidence of first-degree intentional homicide.

"He's a suspect," said Det. Kingston.

The police are calling the alleged father of Amber Wilde's unborn baby the suspect in her disappearance, so Crime Watch Daily tracked him down to get his side of the story.

"I think she was killed. I think she was killed and her body was disposed of," said Det. Kingston.

When 19-year-old Amber Wilde mysteriously went missing, State Highway 29, that runs through the heart of Green Bay, Wisconsin, was under major construction.

The police and Amber's family think she and her unborn baby are buried somewhere under all that asphalt.

Matthew Schneider, the alleged father of Amber Wilde's unborn baby, was building Highway 29 when Amber was last seen alive.

To this day, Matt Schneider has denied any involvement with Amber, claiming he never had sex with her. In fact Schneider says he barely even knew Amber.

"We've pretty much been able to prove that was a lie. That he did know Amber, he did have a sexual relationship with her, and Amber thought was the father of her child," said Det. Kingston.

Police say Amber's phone records, combined with her secret diary, read like a road map for murder. And they say all roads lead straight back to Schneider.

Police believe Schneider was terrified his fiancée would find out the affair and baby, so he panicked and got rid of Amber and the baby for good.

Crime Watch Daily has discovered newly unsealed court documents that name Matthew Schneider as a prime suspect in Amber's disappearance. Search warrants also reveal police have conducted multiple digs along Highway 29 and a massive search on the Schneider family farm, all in an effort to find Amber's body.

Police say Schneider has never offered an alibi for his whereabouts on Sept. 23, 1998, the day Amber went missing, and he's declined to take a polygraph test. And now he's refusing to speak to cops.

Schneider's silence has devastated Amber's family. We wanted to help Amber's family lay some of their misery to rest, so we set out to get some answers from Matthew Schneider.

We got a tip Schneider was on his way home, a home he now shares with the fiancée Amber once confronted, who's now his wife, and their kids. Then suddenly Schneider appears right in front of me.

"I have nothing to say," Schneider told Crime Watch Daily before he went into his house.

Matthew Schneider may have closed the door, but Amber Wilde's case remains wide open, and the FBI has now on the hunt for answers. For now it's Amber's family that's haunted by the unknown.

If you know anything about the day Amber Wilde disappeared or where she might be, contact Green Bay Area Crime Stoppers at (920) 432-7867, or submit a tip to the FBI.