Police arrested a graduate of Chuo University on Thursday on suspicion of stabbing his former professor to death in January at the university's campus in Korakuen, Tokyo, police said.
Ryuta Yamamoto, a 28-year-old part-time worker from Hiratsuka, Kanagawa Prefecture, has admitted to the charges, the Metropolitan Police Department alleged.
He has reportedly refused to say why he killed Hajime Takakubo, 45, a professor in the Faculty of Science and Engineering. Yamamoto said he did not have any specific trouble with Takakubo, according to the police.
Takakubo was found in a restroom bleeding from more than 60 stab wounds on the morning of Jan. 14. He died shortly after from blood loss and damage to the heart, lungs and aorta.
The police believed the attacker had a definite intent to kill him.
DNA found under Takakubo's fingernails matched that of Yamamoto, the police alleged.
The police said Yamamoto graduated from Chuo University in March 2004 and that Takakubo supervised his graduation thesis.
Yamamoto was employed by five companies in three years after graduating but did not hold any of the jobs longer than four months, the police said.
A senior investigator said Yamamoto has a tendency to obsess over certain thoughts once he comes to believe them.
Takakubo was an expert in electronic circuits used in televisions and mobile phones. He belonged to the Institute of Electronics, Information and Communication Engineers, and the Institute of Electrical Engineers of Japan. He was from a family of scholars, with his grandfather and father having taught at Chuo University. His wife teaches at a university.