NEW YORK (AP) — The ex-boyfriend of a police forensic investigator whose naked body was found tied to a bed in a pool of blood pleaded guilty Thursday to manslaughter in her death.

Gary McGurk admitted he hit Michelle Lee over the head and stabbed her in the neck in her apartment on April 27, 2009, prosecutors said. McGurk, 24, faces between 29 and 37 years in prison when he's sentenced next month.

McGurk, who's from County Tyrone, in Ireland, met Lee in 2004 when they were at John Jay College of Criminal Justice studying to be forensic investigators, like the ones made famous on the CBS television crime drama "CSI."

But dating didn't work, and they were "friends with benefits," McGurk said in a statement to police after his arrest.

"Sweet girl. Friends first, herself last," McGurk said in a rambling statement. "She told me that she made bad decisions. I told her that I was a bad decision, joking."

McGurk claimed he and Lee, 24, had rough sex, tying up and choking each other, according to court documents.

Lee's body was discovered by her roommate at their third-floor apartment in the Sunnyside neighborhood of Queens. She was found naked, tied to the bed with burn marks on her abdomen. She had been stabbed and hit with a blunt object.

McGurk admitted tampering with her blood and sending a message to his own phone from her BlackBerry before taking it with him as he left the apartment, Queens District Attorney Richard Brown said.

McGurk, who moved to the United States when he was about 10, had been charged with second-degree murder and had faced up to life in prison if convicted at a trial. His attorneys did not return telephone calls seeking comment Thursday.

Lee started working for the New York Police Department in September 2008 as a criminalist, and she was training in forensic investigations at a police lab analyzing evidence including hair samples, drugs, gunshot residues and bodily fluids. She was going to specialize in narcotics, prosecutors said.

"I think that Michelle would have been especially proud of her colleagues at the NYPD's Queens crime lab who worked tirelessly to make certain that her killer was apprehended and that justice would be served," Brown said.

McGurk said in his court statements he wasn't sure he could handle the life of a forensic psychologist.

"I find crime scene photos and cadavers disturbing," he said.