Serial Killer Cop 'The Werewolf' Convicted of 56 Murders While Serving Life for 22 Slayings

A former police officer in Russia has been convicted of 56 murders while already serving a life sentence for another 22 killings.

Mikhail Popkov, Russia's most prolific recorded serial killer, was convicted Monday of killing at least 56 people between 1992 and 2007, according to a statement from the prosecutor's office in the Siberian city of Irkutsk and carried by AFP.

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Popkov would kill his victims with axes, knives, screwdrivers or blunt weapons after offering them rides home late at night while wearing his uniform, sometimes in his police car.

The murders took place while he was off duty and close to his home city of Angarsk, around 2,550 miles from Moscow. The killings reportedly continued for nearly a decade after he left the police force in 1998.

In 2015, Popkov was convicted of murdering 22 women and was sentenced to life in prison. He later admitted to killing another 59 people, but prosecutors could only prove his responsibility for 56, according to the Interfax news agency.

His victims and alleged victims were all women between the ages of 16 and 40, apart from one man, who was a fellow police officer, the BBC reported. According to the Siberian Times, the killer targeted prostitutes and women who had been drinking, considering them immoral.

Prosecutor Alexander Shkinyov said Popkov would sentence his victims to death "as soon as they agreed to share a drink with him." The Siberian Times also suggested that his crimes were motivated by false suspicions that his wife had committed adultery.

He was arrested in 2012 during a re-examination of cold-case evidence, which included DNA-testing all people known to drive a specific type of car whose tracks were found at the murder scenes.

Prosecutors said Popkov displayed "a pathological attraction to killing people." He was also found guilty of raping 10 of the victims. The former police officer is now serving two life sentences and has had his pension as an ex-policeman revoked, costing him around 24,000 rubles ($358) per month, according to state news agency Tass.

Popkov, dubbed "The Werewolf" and the "Angarsk Maniac" by Russian media due to the mutilation of his victims, is Russia's worst known mass killer, the BBC noted, due to his total of at least 78 convicted murders.

He surpasses "Chessboard Killer" Alexander Pichushkin, who was sentenced to life in prison in 2007 for 48 murders, and Andrei Chikatilo, who was convicted of 52 murders during the Soviet era.

Serial killer Mikhail Popkov stands inside a defendants' cage during a court hearing in Irkutsk, Russia, on December 10. ANTON KLIMOV/AFP/Getty Images