Investigators earlier said that Alexander Pichushkin, who has pleaded guilty to numerous counts of murder and faces life in prison, was suspected of killing up to 62 people.
After Monday's preliminary hearings on the Bitsa Park murders, a journalist asked Pichushkin why he became a killer, to which he enigmatically responded: "Such were the circumstances."
The former supermarket worker earlier explained that with each victim he was getting closer to filling the 64 squares on an imaginary chessboard.
Moscow Prosecutor General Yury Syomin, who heads the prosecution team, said the hearings would be concluded within two months. He also said 41 victims and 98 witnesses for the prosecution were involved in the case.
Investigators believe Pichushkin committed his first murder in 1992, but that his main killing spree occurred between 2001 and 2006. Almost all the murders are believed to have taken place in wooded areas of Bitsa Park in southwest Moscow. Most of his victims were male, but three were women and one was a child.
