The police on Sunday were still trying to identify the body of a man found floating off the docks of a southeast Brooklyn neighborhood, an eerie reminder of an old-fashioned organized crime story.

A passer-by noticed the body wrapped in a blue tarp bobbing on the waves on Saturday morning near East 58th Street and Avenue U in the Mill Basin inlet, the police said. The tarp was wrapped with gray duct tape and the man’s legs were tied with an orange electrical cord, which was fastened to a cinder block, the police said.

The man died of blunt force trauma to the head and his death was ruled a homicide on Sunday, said Julie Bolcer, a spokeswoman for the medical examiner’s office.

It is not uncommon for the authorities to find bodies in New York City waterways, but they are usually found in the spring, when higher temperatures speed decomposition, producing gases that make a body buoyant enough to float to the surface.