Infatuation and jealousy led a Port Jefferson Station man to break into a colleague's Mastic home and fatally stab her boyfriend in the back while he slept, authorities said Thursday.

Tomas Peck, 26, entered Dana Duford's house on Winters Drive at around 5 a.m. on Feb. 10 with a key she was unaware he'd taken, police said.

With a hunter's knife in hand, Peck went into Duford's bedroom and stabbed Tyrone Terry, 21, a North Carolina correction officer, multiple times in the back, officials said.

Assistant District Attorney Nancy Clifford said Terry awoke and struggled with Peck, who continued to puncture Terry through the chest, abdomen and head.

Duford's 5-year-old son woke up during the commotion, Clifford said, and after Terry had fallen unconscious, Peck took the little boy downstairs to the basement and turned on the television for him. Then he went back up and confronted Duford, who'd also awoken.

Peck punched her repeatedly in the face and then choked her until she was unconscious, Clifford said. When she awoke she called 911.

Det. Lt. Jack Fitzpatrick said police recovered the murder weapon blocks from Duford's home.

After the slaying, Peck fled to New York City and then took a bus to Texas. He crossed the border into Mexico, where, according to his attorney, he had been raised for 15 years by his father. During that time, however, Suffolk police were in communication with Peck.

Fitzpatrick said detectives were able to call Peck on his cell phone and that Peck also called the Homicide Squad. He confessed to killing Terry and voluntarily returned to Miami, where he was arrested. He went before a Miami court on Wednesday and was extradited back to New York. He was arraigned Thursday in First District Court in Central Islip and ordered held without bail.

According to the felony complaint, Peck admitted, "Ty was trying to escape when I stabbed him. I knew he was dead because he wasn't moving."

Peck's mother was seated in the third row when her son was brought before Judge John Iliou. As Clifford recounted Peck's actions, the defendant's mother fainted. The courtroom was temporarily cleared as court officers and medical personnel attended to her.

She regained consciousness, crying, and was later escorted out by two correction officers.

After the arraignment, Peck's attorney, Steven Wilutis, of Miller Place, said he'd met briefly with his client, who he described as "very upset." He said Peck contends he was romantically involved with Duford.

"The preliminary information I have is this was a love triangle," he said.

Clifford said there was no evidence to suggest that. She described Peck as being infatuated with Duford.

Terry's family declined to comment.

A woman who answered the phone at Duford's house and identified herself as her sister said Duford had moved away.

"It was too much for her," she said. "She couldn't take it."