CLALLAM BAY — A 68-year-old Clallam Bay Corrections Center inmate who died last week has been identified as a King County resident who was serving three life sentences for three murders committed in the late 1960s.

In 2004, King County prosecutors called John Dwight Canaday “the first known serial killer in Washington,” according to a story in the Seattle Post-Intelligencer newspaper.

Canaday was found unresponsive in an isolated section of the Clallam Bay prison just before 5:30 p.m. Wednesday.

His death appeared to be from natural causes, State Department of Corrections spokeswoman Norah West said, adding that officials are awaiting information from the Clallam County Coroner’s Office.

Deb Kelly, Clallam County coroner and prosecuting attorney, was unavailable for comment Saturday.

Canaday was attended to by prison medical staff and Clallam County Fire District No. 5 paramedics soon after he was found, but to no avail.

The Seattle Post-Intelligencer story also said that Canaday’s 2004 guilty plea for a 1968 murder represented the longest gap between prosecution and murder for any killing prosecuted in the state.

King County law enforcement officers and prosecutors had been working for 36 years to solve the murder of Sandra Bowman, a 16-year-old pregnant newlywed who was bound, stabbed 57 times and left dead in her apartment in December 1968, the newspaper said.

Canaday had been working for Ballard’s water department, the newspaper said, and randomly chose the Ballard apartment Bowman shared with her husband, Thomas Bowman.

Newly available DNA matching technology and a “cold case” squad formed in 2002 allowed prosecutors to charge Canaday with Bowman’s murder, after which he pleaded guilty to the killing.

Canaday already was serving two life sentences for two murders he committed in January 1969: 21-year-old Mary Bjornson, who Canaday bound and strangled in Seattle’s Seward Park, and 20-year-old Lynn Tuski, who Canaday raped and killed after finding her walking to her car near a North Seattle department store, according to the newspaper.

Canaday was originally sentenced to death for these murders, according to the P-I.

He was given a reprieve, however, in 1972 when the U.S. Supreme Court struck down death penalties in Washington and several other states.

Reporter Jeremy Schwartz can be reached at 360-452-2345, ext. 5074, or at jschwartz@peninsuladailynews.com.