Police are investigating the sudden death in Wakayama Prefecture of a wealthy man, who had dubbed himself “Don Juan,” as a possible murder after stimulants were detected in his body, investigative sources said Monday.

The collapsed body of Kosuke Nozaki, 77, was found by his wife, 55 years his junior, on his bedroom sofa on the night of May 24. His housekeeper was also at the home at the time.

He was later confirmed dead and an autopsy found traces of illegal narcotics in his system, while no external injuries were found.

The cause of death was identified as acute circulation failure, and investigators are trying to determine if his death was caused by the stimulant drugs, the sources said.

Nozaki was the president of a liquor sales company and financial businesses in Tanabe, Wakayama Prefecture, an area formerly known as Kishu.

Nozaki was featured in TV programs and magazines after publishing his autobiography in 2016, titled “Don Juan of Kishu: The Man Who Gave 3 Billion Yen to 4,000 Beautiful Women,” likening himself to the mythical European playboy.

His marriage to his current wife in February, when she was 21, was also featured in magazines. In April, he published a sequel to his book, in which he pledged to “have sex with a beautiful woman until I die” and wrote about how to stay fit.

Police have searched Nozaki’s home in Tanabe and related locations in Tokyo on suspicion of murder. They also required persons of interest to undergo urinalysis and have been questioning them.

In 2016, an acquaintance of Nozaki was arrested on suspicion of stealing jewelry and other valuables worth ¥60 million from his home, but she was not indicted. He had his items stolen again in 2017.

Nozaki’s former neighbor in Tanabe said he had been dedicated to his work before attaining a successful career, distributing ads of his business in Tokyo, but that he had few local friends.

“I really feel sorry (for his sudden death) because he was recently positive about making a contribution to his own community,” said a man who knew Nozaki from his childhood.