Kenneth Moreno took the stand Monday in his own trial. He and partner Franklin Mata both face rape and other charges in the December 2008 incident. Mata is accused of acting as a lookout.
The officers helped the drunken woman to her apartment and then returned three times within hours.
The woman says she passed out but awoke to being raped. Moreno's lawyer has said she misremembers what happened.
Mata testified that he nodded off while Moreno and the woman were alone in her bedroom, but Moreno "wouldn't do something like that."
"I know Ken ... that Ken wouldn't do a thing like that," Mata said, under stringent questioning by a prosecutor.
Both Mata and Moreno are on trial on rape and other charges in the December 2008 incident.
A taxi driver had called them to help a drunken woman get out of his cab and into her Manhattan apartment. The officers then returned to her apartment three times within hours, without telling dispatchers they were there or noting the visits in logs. At one point when they were at her apartment, they instead indicated they were responding to what prosecutors say was a phony 911 call Moreno placed about a homeless person sleeping in a building lobby.
Mata said he didn't know at the time about the source of the call. He said he didn't make official note of the visits to the woman because "I didn't think we were doing anything wrong by running up to check on this person."
The woman, who has a corporate job in fashion and is now 29, testified last month that her memories of that night are intermittent and she passed out at times. But she said she unmistakably recalls waking up to being raped in her bedroom and was certain her attacker was one of the officers who had escorted her upstairs.
Moreno hasn't testified. His lawyer says she wasn't raped and misremembers what happened. In a secretly taped conversation with her days later, Moreno alternately denied having sex with her and seemed to admit it, twice saying he'd used a condom. His lawyer says the seemingly incriminating statements were efforts to mollify the woman.
Mata testified that the woman had asked the officers to return and check on her, suggesting they take her keys to do so. Though drunk, she was alert and able to make conversation, he testified last week.
He said Monday that during one of the visits, he heard the woman giggle and saw her touch Moreno's arm while she and Moreno were in her bathroom so she could vomit.
"It seemed flirty," Mata concluded.
On the officers' final visit around 4:30 a.m., Mata testified, he fell asleep for about a half-hour on the woman's living-room sofa after seeing Moreno follow her from the bathroom to her bedroom. Asked whether he knew whether the woman had been raped as she described, Mata said, "I don't. I was in another room."
He awoke when Moreno nudged him and said they were leaving, Mata said. He didn't ask his partner anything about what had happened, he said.
Mata and Moreno have been suspended until a Police Department review after their trial. If convicted, each could face up to 25 years in prison.