EVERETT, Mass. (AP) — Pro wrestling pioneer Walter "Killer" Kowalski died early Saturday from the effects of a massive heart attack. He was 81.

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

An obituary posted at Weir Mac Cuish Family Funeral Home's Web site said Kowalski began his professional career in 1947 as "Tarzan" Kowalski. His hulking 6-foot-7, 275 pound frame and a brutal wrestling style soon earned him a nickname "Killer."