Spokane County sheriff's Sgt. Dave Reagan says 57-year-old Phillip Arnold Paul was last seen Thursday morning in the northeast part of the fairgrounds.
The sheriff's office told KXLY in Spokane that they were "dismayed" that the Eastern State's Hospital didn't notify authorities for more than an hour and a half after they knew he was missing.
"It appears now there was a two hour lapse from the point he disappeared from his attendant to the sheriff's office was notified of his escape and obviously that's a concern to us," Sgt. Reagan told KXLY. "We're concerned that we were not aware that people of his criminal history were being brought to the fair for day trips. As a courtesy we would have liked to have been notified ahead of time."
In 1987, Paul slashed an elderly woman's throat in Sunnyside in 1987, soaked her body in gasoline to throw off search dogs and buried the remains in her flower garden.
He was later diagnosed as being criminally insane and suffering from schizophrenia, KXLY reported.
Paul claimed the voices in this head told him the woman was a witch, according to the station.
He was acquitted by reason of insanity but committed to Eastern State Hospital indefinitely.
Had the institution told the police about the incident earlier, the "odds of catching him would have been much greater," Reagan said.
Eastern State Hospital declined comment.
A store clerk told authorities she saw someone matching Paul's description later in the morning, and Reagan says investigators believe he has gotten outside the fairgrounds.
"His sister tells us he calls his parents in Sunnyside virtually every day and that if he's escaped he's headed home," Reagan told the station.
The fair's director told KXLY that they were unaware a group from the hospital was at the fair.
In 1996, a judge allowed Paul to attend Spokane Community College during the day as long as the went back to Eastern State Hospital at night, according to the station. Two years later another judge ruled he could have overnight visits in Spokane as long as an adult member of his fmaily was present.
It's not the first time Paul has escaped.
In 1990 he walked away from custody and attacked a sheriff's deputy who apprehended him.