Mikhail Popkov, convicted of 56 more murders

A former police officer jailed for murdering 22 women received a second life sentence on Monday for the murder of 56 more people, making him one of modern Russia's deadliest serial killers.

Dubbed the "maniac of Angarsk" after his home city in Siberia, 54-year-old Mikhail Popkov drove victims to secluded spots where he killed them with axes, knives or screwdrivers. Some were also raped.

He was detained in the Russian Far East in 2012 two decades after he began his killing spree and was sentenced to life imprisonment in January 2015 for 22 murders and 2 attempted murders.

He confessed to 60 more crimes, including 59 murders, after he was convicted.

Investigators said on Monday that Popkov had provided evidence allowing officers to exhume the remains of victims killed 15-20 years ago, along with their personal effects and the weapons he had used to kill them.

Investigators said Popkov's victims were women aged from 16 to 40. He also killed one man, a fellow police officer.

A state prosecutor told the court that Popkov had a phenomenal ability to recall minute details of his crimes, including the clothes, tattoos, and jewellery worn by his victims, RIA news agency reported.

Andrei Chikatilo, known as the Rostov Ripper, was convicted in 1992 of killing over 50 people. He was executed.

In 2007, supermarket worker Alexander Pichushkin was convicted of killing 48 people. He became widely known as the chessboard killer as he had hoped to put a coin on every square of a 64-square chessboard for each of his victims.