If the Ice Man did all the stuff he claimed it would indeed be pretty incredible. Many people think much of it was made up. He did do enough that he is in that serial killer area though. Others are Thomas Pitera ( about 60 murders), Roy Demeo and his crew ( up to 200). Roy was one that the Iceman talked about but the guys still living from his crew were " Kuklinski who"? Even John Gotti refused a contract on Roy Demeo out of fear of him. There are a bunch of those guys that got from 40 to a hundred murders over their careers. Some Cartel killers have 200 to 500 murders. Now some of them are pretty sick puppies.
If you want to readup on a drug dealing sicko try : Adolfo Constanzo https://en.wikipedia.org/wiki/Adolfo_Constanzo
Wiki only touches on his degeneracy. A true "ritual" murderer.
The 1930's through 40's NYC group known as "Murder inc." ( about a thousand murders ) had about 10 guys of that group who were psychopathic freaks that enjoyed the torture part of their jobs a bit too much. It's kind of fun reading about this stuff until you see police reports, autopsy and crime scene photos. Those were the clothesline and ice pick, pliers and propane torch types. I can kill for my country but that lifestyle repels me greatly. No amount of money would ever be enough!.