Sherill, NY (WIBX) - The trial of the man accused of stabbing his girlfriend's six-year-old daughter to death in Sherill last year is underway in Oneida County Court. David Trebilcock chose not to have a jury trial, and Judge Michael Dwyer is prosiding over his case. He has pleaded not guilty by reason of mental illness.

The prosecution's first witness was the victim's mother, Allison Belius. Belius told the court that the night before Trebilcock killed her daughter Lauren, he told the victim that she would be famous one day. According to Bellius, he also told her how special she was and how the girl was his favorite. She told the court that on this particular evening, Lauren was "acting silly" and singing an "I love you" song she made up for her mother.

Bellius told the court that she let Trebilcock move in with her and her three children on December 1, 2010. He was living in Rome prior to the move. She described him as not only her lover but her "best friend." She said in the summer of 2011, they were planning a family vacation to Florida. She said Trebilcock became hesitant about the trip as they neared the travel date. According to her testimony, Trebilcock told her that he could get arrested in Florida, saying, 'he would not make it to Disney World' because he got in trouble for having sex with a 12-year-old girl at a party when he was 19-years-old. Trebilcock is from Florida.  He also told Belius that he had been cheating on her.

Belius testified that she was upset about the information but "rationalized" it because she said, "twelve-year-old's don't always look like twelve-year-old's. And, it was at a party and everyone was drunk and high." She said Trebilcock's age at the time also played a role in her rational of the circumstances. She told the court that she maintained the relationship despite this information.

She said at one point, Trebilcock revealed something else to her--he had a "sex-addiction." She said he told her that if anyone found out about his on-line activities, he would get in trouble. She said when they would argue or when she would get upset with him, he would walk around with a bible. She said she never saw him read the bible. He just kept it on his lap and take it with him when he would smoke in the basement. She said although she found his behavior "unusual," it did not raise any alarms because he would take it with him when he worked at a nursing home.  She said Trebilcock at one point worked as a Teacher's Aid but was unemployed most of the time they maintained a relationship.

She told the court that Trebilcock made several attempts to leave the relationship but she convinced him to stay each time he wanted to leave. She said that Trebilcock would tell her, "that he didn't want to hurt her." He would also say, according to Belius, "that he should leave because he had hurt her too much."

She said the weekend before Trebilcock stabbed her daughter to death, he again tried to leave the relationship. She said the kids were with their father that weekend. She said his mood changed from happy to that of frustration and what she characterized as "guilt." She said they got into an argument because she did not want him to leave. Also, he wanted to call his ex-girlfriend and former roommate to come and pick him up, which did not sit well with Belius who told the court that she did not have a good relationship with his ex-girlfriend and did not want her at the house. She said, "I told him not to go and to give the relationship more time."

Later that weekend, she said she saw him go to the back yard and call his ex-girlfriend for a ride. She said when confronted again, "he just said that he felt that he needed to leave." She said she threatened him that if he did leave with this person, she would not allow him back into the house. She said she was also concerned for his safety, "I felt like he was carrying a lot of guilt that week and thought that he might kill himself," she said.

Belius said Trebilcock left, but returned later that night around 8:30 p.m. "He acted like nothing was wrong and that everything was fine now," she said. She told the court that Trebilcock professed his love for her and the children that night supposedly saying that he now sees that Belius loves him. She accepted him back into their home. She also told him that his bible was in the garbage to which he replied, "That's OK, I don't need it anymore." She says that was the weekend Lauren was acting "very silly" when she and her siblings returned from their weekend visit with their father.

Belius said when it was time to put her children to bed, Erika--Lauren's twin sister--came back to the kitchen area for a drink. She decided to make cool-aid with her daughter. She said they accidentally spilled the cool-aid and were about to make more when she heard a commotion concerning Lauren, who seemed very happy prior to going to bed. Belius says when she went to the bedroom, she heard Lauren say that she was going to "throw-up" and that she was "sick to her stomach." She described Lauren as looking "flushed" and red in the face. She said she also saw Trebilcock in the child's room. "He was just standing there," she said.

She told the court that Lauren was "very upset" and when she asked her what was wrong, she just kept saying, "I don't know, I don't know." Belius says she noticed that her daughter was looking at Trebilcock, who was still standing in the room, as she was saying this. She said she was confused by the sudden turn of Lauren's behavior but thought it could be due to the one-piece sleep wear she had on.

She said later that evening her then 8-year-old son, Nolan asked if he could speak to her in private. She said she followed him to his room where he told her about a troubling conversation he had with Trebilcock. Belius said that her son told her that Trebilcock said to him, "very soon something bad's going to happen." According to her testimony, her son also said that Trebilcock told him that the world was full of bad people. She said Nolan thought that he was referring to "2012." After calming her son down, whom she said "loved" Trebilcock and frequently played video games together, she proceeded to talk to Trebilcock about the incident.

She said she was upset with him and told him to apologize the next day. She said Trebilcock told her that he felt terrible for what he did and wanted to apologize to Nolan right away. She said after this incident, the two stayed up together, had sex and went to bed. She said she fell a sleep with him next to her.

Belius said on Monday, July 18th she woke up to her daughter Erika screaming from the bed room. She jumped out of bed, ran across the hall and started pushing on the door. She said it took her about about three minutes to gain entry. She said she had to squeeze her way into the bed room that was barricaded with a dresser. "I saw him standing on a ladder stabbing Lauren repeatedly on her back," she said. Belius said as she pulled Trebilcock away from her Lauren, he grabbed a hold of railing on the bunk bed she shared with her twin sister and broke it as he fell to the ground.

She said she yelled, "Why are you doing this?! Why are you killing my baby?!" She said he replied, "She's not a baby, she's bad!" She said Lauren then rolled off the top bunk bed and fell to the floor, landing on her stomach. She said Trebilcock was stabbing himself at this point. Belius, who is a nurse, says she noticed that Lauren was still breathing but not much. She said as she attempted to give her mouth-to-mouth, Trebilcock came back toward them and reached over her to stab Lauren in the neck. She said he then started to stab himself in the chest. She said he then grabbed his penis and made as if he was going to cut it off.

She said as she was still struggling to perform CPR, Trebilcock came back from behind her and stabbed Lauren in the chest. She said he then turned the knife on her and tried to stab her in the chest. She said she grabbed the blame of the knife and was able to take it away from him. She said she stabbed him in the neck with it. She said as she was fighting with Trebilcock she could still hear Lauren trying to breath and she went back to administer CPR.

She said during this time, she did not know where her son was, but said Erika was cowering near the corner of her bunk bed yelling, "Stop it! You're killing my sister. We're going to call 9-11 on you! Belius says when she was stabbing Trebilcock she could hear Erika yelling, "Stab him mommy! Stab him!."

The prosecution called several witnesses to testify. Including the neighbors who came to help and the law enforcement officials who were called to the scene. One neighbor said when she came from across the street she noticed that Lauren was naked from the waist down and decided to get some of her own daughter's clothes to cover her up. Another neighbor testified that she heard a woman screaming for help and she got into her truck and drove over to help. Prosecutors also played the 9-11 tape that another neighbor made after he woke up to banging on his front door and calls for help. State police officials who arrived on the scene testified that they found Trebilcock nude and bloody in the child's bedroom.

Testimony continues tomorrow in Oneida County Court.