Prosecutors have decided to indict a 25-year-old woman suspected of the murder around three years ago of her wealthy elderly husband who was known as the "Don Juan" of his locality in western Japan, investigative sources said Tuesday.

Saki Sudo, who is set to be indicted on Wednesday's deadline for her detention, was arrested on April 28 for allegedly causing Kosuke Nozaki, 77, president of a liquor sales company and real estate business, to ingest a lethal amount of an illegal stimulant drug in May 2018 only three months into their marriage, with the deliberate intent to kill him.

Nozaki's suspicious death attracted attention as he had gained notoriety for publishing an autobiography titled "Don Juan of Kishu: The Man Who Gave 3 Billion Yen to 4,000 Beautiful Women" in 2016, likening himself to the mythical Spanish playboy.

According to the sources, Sudo has denied the charge and maintained silence.

While there is a lack of direct evidence, it is believed that the Wakayama District Public Prosecutors Office feels it can establish guilt on the basis of circumstantial evidence.

According to the sources, analysis of Sudo's smartphone revealed that prior to the incident she had searched for information about stimulants and how to make a murder look like someone had died of an illness.

Location data on the phone also revealed that Sudo had been in the same place in Tanabe, Wakayama Prefecture, at roughly the same time as a trafficker suspected to have provided the drug to her.

Security camera footage of Nozaki's house also did not show any other person entering or leaving during the four hours before and after dinner that he was alone with Sudo, when he is presumed to have ingested the stimulant drug.

With suicide ruled out, prosecutors have concluded that Sudo poisoned Nozaki.