A police inspector responsible for destroying seized drugs was found with £700,000 of drugs at his home - including 11kg of cocaine "jammed" in his washing machine.
Keith Boots, 55, was in charge of a police store where confiscated drugs were kept to be later destroyed.
But Leeds Crown Court heard that instead of disposing of them, he stole large amounts to re-supply to the streets.
When officers raided his Bradford home in December 2014 they found 11kg of cocaine in his washing machine, as well heroin, ecstasy, crack and cannabis.
"Keith Boots was a criminal masquerading as a police officer who stole class A drugs from the force which he then intended to resupply to the criminal fraternity," said Detective Superintendent Simon Bottomley from West Yorkshire Police.
"The actions of Boots were simply inexcusable. Whilst his hardworking and honest colleagues were doing all they could to take illegal drugs off of the streets he was stealing them back and seeking to redistribute them."
Officers raided his home after finding drugs had gone missing from the police store.
"What was found on the ground floor would have kept a 1970s rock star, as well as his band, entertained for weeks," prosecutor Paul Greaney told the Leeds court.
Boots, who had been an inspector for 10 years, was found guilty of various offences including conspiracy to pervert the course of justice, theft, and possessing drugs with intent to supply.
He was dismissed from the police in March 2016 and will be sentenced by the court next week.
His son, Ashley Boots, 30, of Weatherhouse Terrace, Halifax, was also found guilty of conspiracy to supply controlled drugs, conspiracy to steal and conspiracy to pervert the course of justice.
He admitted six charges of possessing drugs with intent to supply and one of possessing ammunition.
A third man, Ian Mitchell, 28, of no fixed address, was found guilty of conspiracy to pervert the course of justice.