Green River killer Gary Leon Ridgway sent an anonymous letter to the Seattle Post-Intelligencer nearly 20 years ago in what the newspaper said Friday was a "brazen attempt to throw off investigators."
Authorities at the time wrongly concluded it wasn't from the real killer, the paper said.
Now, police say Ridgway admitted writing the letter when he began confessing this summer to killing 48 women.
The paper said it had turned the letter over to investigators in 1984 and never reported on it, in part because of doubts about its authenticity.
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"He brought up the letter during interviews," King County Sheriff Dave Reichert told the newspaper. "He took credit for writing it and sending it. He went through and explained what each comment meant."
The letter was poorly typed and almost entirely without spaces between words.
It began: "whatyou eedtonoaboutthegreenriverman" and "dontthrowaway." Typed at the bottom was "callmefred."
The letter mentions evidence, such as necrophilia and fingernails cut off victims. There are red herrings, such as saying the killer smoked and chewed gum.
The letter landed on reporter Mike Barber's desk in February 1984.
Concerned about preserving evidence, Barber made a photocopy and slipped the original into a plastic bag.
An FBI evaluation was a bust. The letter had already been handled by too many people, and an FBI psychological profiler said it was probably the work of "someone inside the task force seeking undue attention."
Still, Barber kept a copy in his files. And the P-I ran a classified ad asking "callmefred" to contact the paper, but nobody did.
"It is now clear that the letter was Ridgway's brazen attempt to throw off investigators," Barber wrote Friday. "It was the only known time he surfaced to communicate through the news media."
Barber said he still ponders the meaning of the last line, "Oehatkindofmanisthis," apparently "What kind of man is this?"
If Ridgway wants to explain it, Barber said, "he knows where to find me."