A bar worker at a popular Times Square karaoke club was arrested Thursday after confessing to beating a woman to death with a pipe on the club's roof during an argument, police said.

Syed Rahman, 24, admitted he smashed Ingrid Rivera over the head at about 2:45 a.m. Monday during a birthday party for rapper Lil' Kim that the victim had paid to attend, Police Commissioner Raymond Kelly said at a news conference. Her body was discovered Wednesday afternoon.

It was unclear what Rahman and Rivera, who had met for the first time inside Spotlight Live club that night, were arguing about. But a friend of Rivera pointed police to Rahman by telling them she had fought off his sexual advances on the roof shortly before the slaying, Kelly said.

Rahman _ who had worked at the club for four years and had no previous criminal record _ was arrested on a charge of second-degree murder, which carries a penalty of up to life in prison upon conviction.

Rahman kept his head down and said nothing when officers escorted him out of a police station. Authorities did not have the name of his lawyer.

The medical examiner ruled the death a homicide Thursday after an autopsy found that the 24-year-old Rivera died from a blow to the head.

Police said Rivera was a Lil' Kim fan who arrived at the party around 9:30 p.m. with a bouquet she had hoped to give to the rapper. During the evening, she and her friend spoke with Rahman while drinking at the bar.

At one point, Rivera was kicked out of the club for accidentally entering the men's rest room, police said. Rivera's friend said that around the same time, Rahman lured her to the roof by claiming Rivera was there.

When the friend rebuffed the suspect, he located the victim outside and "told her he could get her back in," Kelly said.

He took Rivera in through the employee entrance, then up to the roof in a service elevator, police said. Once there, he beat her inside a utility shed, killing her instantly, police said.

The man left the club at around 3 a.m., even though he was scheduled to work until 5 a.m., and went to Central Park and slept for a few hours, police said.

Police said that after Rivera's mother reported her missing on Tuesday, officers went to the club on Wednesday to review security videotape and do a floor-by-floor search of the five-story building. After they left, a repairman doing work at the club stumbled upon Rivera's body tucked away in the utility shed.

Officers found Rahman on Wednesday at an upper Manhattan apartment he shares with his parents. Continued...