The 33-year-old former supermarket worker also claimed to have killed a total of 63 people - one short of his target figure, the number of squares on a chessboard.
"I have been charged over 52 episodes... I thought it would be unfair to forget about the other 11," he said, speaking from his cage in the courtroom.
When the judge interrupted him, saying he could only testify on victims listed in the case, he retorted: "So 63 doesn't interest you? Even though the bodies have been found?"
Pichushkin, who killed most of his victims between 2001 and 2006 in wooded areas of south Moscow's Bitsa Park, told the court he had begun killing in 1992, long before his main spree. He recounted his first murder, when he strangled a 19-year-old classmate named Odeychuk, and threw him down a well.
The two young men had planned to murder an acquaintance, but when Pichushkin realized that his accomplice was incapable of seeing the job through, he did away with him, the killer told the court.
"For him it was a game, but for me it was no game. Not everyone is capable of killing. I realized that he could not be an accomplice, and I decided to kill him."
"A first murder is like falling in love for the first time - unforgettable," he said. "It made a very long-lasting impression on me, and for 14 years I did as I pleased. I got careless, so there is no need for the police to take credit for catching me... I'm a professional."
Pichushkin was arrested in Bitsa Park on June 16, 2006, 11 days after finishing off his final victim and leaving her body in a stream running through the park.
During Tuesday's hearings, Pichushkin pleaded guilty to four of the five counts of murder currently under consideration in court.
Most of the self-professed killer's targets were elderly people walking alone in the park, but three were women and one was a child. Pichushkin said that initially he dumped the bodies in nearby sewage works, but became frustrated that his murder spree was going unnoticed and began leaving the bodies out in the open.
The killer would lure his victims into the woods, often inviting them to drink with him, and would murder them by battering them on the back of the head with a heavy object, usually a hammer.