Perez, 60, of Waterville died on Dec. 12 at Central Washington Hospital of stroke-related complications, The Wenatchee World reported Wednesday.
His daughter, Michelle Valdez, confirmed his death to The Associated Press.
As the city's chief sex crimes investigator, Perez arrested dozens of Wenatchee Valley adults between 1994 and 1995 on suspicion of sexually abusing children, sometimes in bizarre, ritualistic fashion. His investigation, with state Child Protective Services agents, ensnared 42 Chelan and Douglas County residents, 28 of whom were convicted or pleaded guilty, the newspaper reported.
Of the cases that ended in convictions or guilty pleas, 18 were thrown out or overturned on appeal after Perez's tactics were investigated by a specially appointed appellate judge. The investigation found that Perez coerced suspects, many poor and developmentally disabled, into making false confessions, and coached testimony from witnesses.
Two key victims were in Perez's foster care at the time. Both later recanted their claims of sexual abuse.
By 2004, the city of Wenatchee had paid out more than $7 million in jury awards and settlements to claimants who were falsely accused. The last civil lawsuit against the city was settled in 2011 for $120,000, the paper reported.
The case resulted in changes in state law regarding foster care, sex-abuse investigation and mental-health institutionalization involving children, but Perez had no regrets.
"If I were an investigator charged with investigating the cases today, I'd do it exactly the same way," Perez said in 2004.
One of the central figures in the case who was acquitted, East Wenatchee Pastor Roby Roberson, told KPQ-TV he always expected an apology but never received one.
Retired police sergeant Mike Magnotti said protecting children was the first priority for Perez.
"As a police officer he did his very best to serve his community," Magnotti said.
Perez is survived by a son and daughter.
Information from: The Wenatchee World, http://www.wenatcheeworld.com
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