Designer Sylvie Cachay (center) walks the runway at Syla by Sylvie Cachay 2009 collection fashion show during Mercedes-Benz Fashion Week.
The 33-year-old woman found dead in a bathtub at the swanky Soho House hotel Thursday has been identified as a gorgeous Manhattan fashion designer, a source said.
Cops were questioning Sylvie Cachay's boyfriend, Nicholas Brooks, the son of sleazy Oscar-winning songwriter Joseph Brooks.
No one has been charged with a crime and the medical examiner has not released a cause of death.
Cachay's body was discovered about 3 a.m. inside the exclusive Ninth Ave. hotel, with bruises on her neck, sources said.
A friend said Cachay and Brooks, who had been dating for about two months, had a rocky relationship.
"I don't think it was a healthy relationship," said the pal. "I just think he's unstable from what she's told me."
The friend described Cachay, whose line of clothing caught the attention of Vogue editor Anna Wintour, as a "talented, affectionate" person who lit up a room.
"The world lost a beautiful person," said the friend. "She just had a smile that radiated the room."
"It's beyond understanding," Cachay's mother, Sylvia, said at the family home in McLean, Va.
"She was so beautiful," she said. "She was an artist. She was a fashion designer. She had her own company. She was an entrepreneur. A girl that spoke four languages. She went to the best schools."
Cachay's brother, Patrick, called her "a spectacular person, very caring."
"She had a bright future," he said. "That's all I can say right now."
Investigators initially suspected that Cachay, a member of the SoHo House, died of a possible drug overdose, but are now investigating whether she was strangled.
There were also signs that her hair caught on fire, leading cops to suspect she was smoking drugs before she ended up in the tub.
Sources said Cachay and her 24-year-old beau checked into the hotel together and settled into a room on the fifth-floor.
Cops were summoned there after the bath water, which was still running, flooded the tub and leaked down into the room below.
When police arrived, Cachay was found alone and unconscious, wearing a sweater, shirt and underwear. Paramedics pronounced her dead at the scene.
Cops discovered some prescription drugs in the room, but no illegal narcotics were found, a source said.
Brooks returned to the room about 3:30 a.m. to find police there, a police source said.
Joseph Brooks, 72, who penned the '70s ballad "You Light Up My Life," was indicted last year on 82 counts of sex related charges for preying on nearly a dozen young starlets.
The Soho House is a private club and hotel that verifies card-carrying members at the front desk.
The private club boasts a 24-room hotel, a screening room, and rooftop pool.