Former supermarket worker Alexander Pichushkin confessed to killing 63 people with the goal of marking each death on a chessboard, which has 64 squares.

Prosecutors last month charged him with 49 murders committed between 2001 and 2006 in a park on the edge of Moscow.

Though he claims to have killed several people years earlier, prosecutors had focused on the series of killings that occurred in Bittsa Park in 2001, leading to his nickname as the "Bittsa Maniac." Most of the victims were men, whom Pichushkin had lured to the park with the promise of a drink of vodka to mourn the death of his "beloved" dog.

Pichushkin allegedly killed 11 people in 2001, including six in one month, prosecutors said, adding that he killed about 40 of his first victims by throwing them into a sewage pit and in a few cases strangled or hit them in the head, prosecutors said.

From 2005, he began to kill with "particular cruelty," hitting his intoxicated victims multiple times in the head with a hammer, then sticking an unfinished bottle of vodka into their broken skulls, prosecutors have said. He also no longer tried to conceal the bodies, leaving them at the crime scene.