Sylvie Cachay's half-clothed body was submerged in the water faceup, with bruises on her neck and a bite mark on her hand, police sources said.

There were half-empty pill bottles near the cream-colored tub. Cachay, 33, wore only a black shirt and underwear, sources said.

The medical examiner was trying to determine if she was strangled. No one was charged.

More than 18 hours after the body was found in the fifth-floor hotel room, police were still grilling Cachay's party-loving boyfriend, Nicholas Brooks, 24.

The couple quarreled often - even when they'd hit the town, sources said.

"She would always pay, they would always be fighting," said a source at a West Village bar. "They were s----faced most of the time."

Cachay's publicist said the designer and Brooks - whose father is accused of raping starlets - had a troubled relationship.

Two weeks ago, Cachay, who had been divorced for years, wrote an email complaining her unemployed beau was acting erratically.