Amarandra Sharan, appointed by the Supreme Court to examine the documents related to the assassination, said in his report: "The ideology, the assassin and the bullets that pierced Gandhi, and the weapon have been identified. There is no scope for any further probe."
A petitioner had last year claimed that Mahatma Gandhi was killed by a second assassin who had fired a "fourth bullet".
Mahatma Gandhi was assassinated on January 30, 1948, by Nathuram Godse, who was hanged along with two others.
The court had said that a fresh investigation would achieve nothing in the seven-decade-old case, but asked Mr Saran to assist in deciding the case after the petitioner, Pankaj Phadnis, claimed to have documentary evidence to prove that Gandhi's real killer was never caught.
A fourth bullet was recovered in Gwalior, Mr Sharan said, and it didn't match Nathuram Godse's pistol.
Petitioner Pankaj Phadnis is the founder of 'Abhinav Bharat'. He moved the Supreme Court after his petition was dismissed by the Bombay high court.