He apparently fell into the Hudson River while trying to board his boat in Manhattan.
The New York City medical examiner's office said late Monday that more tests are needed to pinpoint the precise cause of Michele Savoia's death.
Police divers recovered his body in the icy waters off Chelsea Piers on Sunday. He was last seen leaving the Marquee nightclub around 4 a.m. Thursday.
Savoia, although not widely known outside the fashion world, enjoyed a loyal following among fellow aficionados of the stylish 1930s and 1940s.
After he was reported missing, police issued a photo (above) that showed Savoia posing in a big fur coat, rakish hat, black vest and pinstriped pants.
Savoia's client list included stars such as Robert DeNiro, Mickey Rourke and Chris Noth. He designed costumes for the Evita revival starring Ricky Martin.
"He could at times be a wild man," says a close friend, Kevin James Dalton.
"You never knew what he was going to do. He'd always surprise you."