(AP) – The head of the NAACP Salt Lake City branch is asking Missouri Gov. Jay Nixon to commute a death sentence for a serial killer who killed two Salt Lake City joggers in 1980.

Joseph Paul Franklin is scheduled to be executed next week for the 1977 murder of a Missouri man outside a synagogue. He was also convicted in the 1980s killings of 20-year-old Ted Fields and 18-year-old David Martin, both black men.

Jeanetta Williams, president of the NAACP’s Salt Lake Branch, says in a letter to Nixon that the execution costs more than keeping Franklin in prison for life.

Franklin has claimed responsibility for nearly two dozen other killings and many other crimes. He admitted shooting Hustler magazine publisher Larry Flynt in 1978 but was never charged.