Police held a 46-year-old man in custody Nov. 23 on suspicion of murdering a former vice health and welfare minister, and his wife, investigative sources said.

Takeshi Koizumi, suspected of involvement in the murder of a former top bureaucrat and his wife, is taken from Kojimachi Police Station in Tokyo on Nov. 23. KYODO PHOTO

Takeshi Koizumi was arrested on suspicion of a weapons violation after he turned himself in on the evening of Nov. 22, reportedly saying he murdered the couple in Saitama and assaulted the wife of another former vice health minister in Tokyo.

"I was angry because my pet was killed by a health center in the past," Koizumi was quoted by police sources as saying.

Police searched Koizumi's apartment in Saitama on Nov. 23.

When he turned himself in to the Tokyo police, he had two bloodstained knives.

Koizumi went to the Metropolitan Police Department headquarters in the Kasumigaseki district at around 9:20 p.m. in a vehicle that had a license plate indicating it was a rental car. He was later taken to a police station in Chiyoda Ward for questioning.

A joint investigative team of the Tokyo and Saitama police had been looking into the possibility that discontent over pensions could be behind the high-profile attacks, as both former vice ministers were involved in pension policy.

Koizumi, who is registered as a resident of the city of Saitama, had eight survival knives, a pair of sneakers and a cardboard box in the car when he turned himself in.

Police said one of the sneakers matched a print found near the house of former Vice Health Minister Kenji Yoshihara, whose wife was stabbed at their home in Nakano Ward, Tokyo.