BALTIMORE – A triple murderer was put to death by injection Thursday after a week of appeals in which his lawyers claimed the execution method was potentially painful and unconstitutionally cruel.

With his appeals exhausted and Gov. Robert Ehrlich declining to grant clemency Thursday, Steven Oken was executed at 9:18 p.m., a Maryland prison spokeswoman said.

Oken, 42, was executed for the 1987 rape and murder of Dawn Marie Garvin, a 20-year-old newlywed. He also was convicted of killing Patricia Hirt, his wife’s sister, and Lori Ward, a motel clerk in Maine, during a 15-day spree.