Zwillman's death definitely was suspicious. He was found hanging from a joist in the basement of his home, with his feet barely off the floor; and yes, there were markings on his wrists. He had been drinking heavily. He was in serious trouble with the law (jury tampering, among other things) and his mob rivals were pressing him.

But the Essex County investigator who probed the death, Brendan Byrne (later NJ Governor), ruled it a suicide. Longy's biographer, Mark Stuart, in his book, "Gangster #2," takes Byrne's word that it was a suicide. He says Byrne had an unimpeachable reputation for integrity--"a real Boy Scout," in Stuart's words.

Stuart's book is the only bio of Zwillman that I know of. You won't find it in bookstores, but you can probably get a used copy for a reasonable price at www.abebooks.com. I've used them extensively, and they're reliable.