EVERETT, Mass. (AP) – Pro wrestling pioneer Walter “Killer” Kowalski has died from the effects of a massive heart attack. He was 81.

Kowalski died at Whidden Hospital in Everett early Saturday, 12 days after his family decided to take him off life support. Kowalski had been in critical condition in the hospital since his heart attack on Aug. 8.

His death was confirmed by a funeral director at Weir Funeral Home in Malden and on Kowalski’s Web site.

The 6-foot-7, 285 pound Kowalski earned his nickname in 1954 after brutally dropping opponent Yukon Eric during a match in Montreal. He later became famous for various moves, including a stomach vice grip called the “Killer Clutch.”

After retiring, Kowalski opened a wrestling school in Malden.

He leaves his wife, Theresa. A memorial service is scheduled at Weir Funeral Home on Wednesday.