Shinji Miyadai. (Kyodo)

The man sought by police over a knife attack on Japanese sociologist Shinji Miyadai at a university campus in Tokyo last November apparently committed suicide the following month, police said Wednesday.

Miyadai, a 63-year-old academic known for his writing on girls dating for money and the now-defunct AUM Shinrikyo doomsday cult, was seriously wounded in the assault that took place on a path at Tokyo Metropolitan University's Minami-Osawa campus in Hachioji on Nov. 29.

The police intend to refer the case against the deceased suspect to prosecutors following further investigation.

The 41-year-old man is believed to have killed himself on Dec. 16, around two weeks after the incident, the police said. His mother, who lived with him, found him dead at their home in Sagamihara in Kanagawa Prefecture south of Tokyo the following day.

Police conducted a search of the home Wednesday.

Although the suspect left a note which included an apology to his family and friends for causing them difficulties, he did not outline a reason for killing himself or for the attack on Miyadai.

Police are continuing to investigate the suspect's motive in the case. He was not a graduate of the university, and Miyadai has said he has "no idea" who the suspect was.

Police had released a series of images of the suspect including one showing him riding a bicycle.

Investigators said earlier that they obtained DNA that appeared to be his from a plastic bottle he was seen throwing away in security camera footage about 2 to 3 kilometers from the scene.

Police had described him as a heavyset man in his 20s or 30s standing about 180 or 190 centimeters tall with short hair and dressed in a black jacket and pants.

He fled the scene after the attack and was being sought on suspicion of attempted murder. His identity has not yet been made public.

Miyadai sustained serious injuries across his body in the attack, and was released from hospital in December. Upon leaving care, he said that while he had "suffered serious physical damage," he was psychologically unscathed.

The sociologist rose to prominence in the mid-1990s with controversial work including books examining cases of high school girls and other young women entering paid relationships with older men. He has also been an active television and radio pundit, as well as a film critic.

Related coverage:

Assaulted sociologist Shinji Miyadai leaves hospital, ready to resume work

Sociologist Shinji Miyadai seriously hurt in Tokyo blade attack

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