Nicholas Brooks, the son of "You Light Up My Life" songwriter Joseph Brooks, was charged with attempted murder and strangulation in the death of Sylvie Cachay. He pleaded not guilty.
Cachay was found Thursday around 3 a.m. in her room at the Soho House hotel.
Police are treating the death as a homicide, but Brooks cannot be charged with murder until the medical examiner's office rules the death was a homicide.
The medical examiner's office has not ruled on a cause of death pending toxicology test results, which could take days.
Police had obtained a search warrant that also allowed them to take photos of Brooks. He has been with police since Cachay was discovered in the hotel bathtub. Police were looking for any possible signs of struggle or trauma, said chief NYPD spokesman Paul Browne.
The 33-year-old Cachay, wearing a black top and underwear, was found submerged in the oval tub, face-up after hotel staff noticed the ceiling below her room was leaking. Investigators said she had some red marks around her neck and a bite mark on her hand.
A bottle of prescription pills was found in the room, but no illegal drugs were found.
Cachay lived in an apartment in West Village. Investigators removed evidence from Sylvie Cachay's apartment on Friday.
She also had a membership to the exclusive Soho House Hotel frequented by celebrities. That meant she had access to the rooftop pool, where "Sex and the City" episodes were filmed, and was able to rent one of the 24 guests rooms at a discount. The hotel has hosted stars like Nicole Kidman and Naomi Watts.
The last hours of Cachay's life are a tangled mess of fire, drugs and, police believe, murder.
Investigators said on Wednesday night that a candle lit by Brooks started a fire inside Cachay's apartment. The couple put out the fire, but they decided to go to the hotel because of the smell.
At 12:30 a.m. on Thursday, the couple checked into the hotel. Employees heard them arguing and she called Brooks "a stoner" in front of them, according to police.
For the next hour, Brooks was frantically in and out of the room for no obvious reason.
According to police, between 1:45 and 2:15 a.m. surveillance video indicates he was in the room.
At 2:16, he left, and by then water was already dripping into the room below.
At 2:30 a.m., hotel workers checking the leak found Cachay already dead in an overflowing bathtub. She was partly dressed.
At 3:30 a.m., Brooks returned to the hotel room, where he was met by police.
A defense lawyer for Brooks says the woman was "absolutely fine" when the boyfriend last saw her at a posh Manhattan hotel. Attorney Jeffrey Hoffman said Saturday that Brooks was "not guilty of any criminal charges in this case."
Cachay and Brooks had been dating about six months, and investigators said some of her friends told them he was erratic. The woman's mother, Sylvia Cachay of McLean, Va., outside Washington, said the two started dating after Sylvie's poodle was struck by a car and killed.
"He helped her through all this process, and they became boyfriend and girlfriend," she said. "Sylvie always had this idea of helping people, and I think this boy needed help in directing his life."
But on a family vacation in Cancun just two weeks ago, Sylvie told her mother the relationship was over.
"She told me, 'Mommy, we are just friends right now. He's trying, but I told him that I don't want to have a serious relationship or consider marriage if he does not change,"' the mother said.
"My heart is just broken," she said.
Cachay grew up with dual citizenship, splitting her time between Peru and McLean. She graduated from Marymount University with a degree in design. She worked for Victoria's Secret, but left the lingerie empire in 2006 to start a swimsuit collection, but had been working at fashion houses again after the economy tanked and she lost her backing.
Brooks' Academy Award-winning father is awaiting trial in an unrelated case. The 72-year-old was accused of raping 11 women he lured to his apartment with the promise of a starring role in a movie. He has pleaded not guilty to sexual assault charges and is free on bail.
He won the Oscar for Best Original Song for the 1977 ballad "You Light Up My Life." He also wrote and directed the movie "You Light Up My Life," about a comedian who has a one-night stand with a director.
Jeffrey Hoffman, who represents the elder Brooks, said the father hasn't spoken to his son since Cachay's death.
"I spoke to him within the last few months and I was unaware he had a girlfriend," Hoffman said.
Information from The Associated Press used in this report