WAKAYAMA (Kyodo) -- A Japanese court on Thursday acquitted a 28-year-old woman of murdering her wealthy elderly husband who called himself the "Don Juan" of the western Japan area where he lived, ruling it could not discount that he may have mistakenly taken a lethal dose of illegal stimulant drugs.

Saki Sudo was charged with causing 77-year-old Kosuke Nozaki to ingest a lethal amount of a stimulant on May 24, 2018, just months after they got married, according to the indictment. Sudo denied the charges, saying she did not kill her former husband.

In handing down the ruling, Presiding Judge Keiko Fukushima of the Wakayama District Court said that as it was the first time Nozaki had used the stimulant, "it cannot be stated that there is no possibility he ingested a lethal amount by mistake."

With no direct evidence to tie Sudo to the alleged crime, the trial was fought over whether a criminal incident had taken place, and if she was acting with criminal intent.

Prosecutors had sought a life sentence, claiming Sudo, who received a monthly allowance of 1 million yen ($6,600), married Nozaki for his money and to inherit his fortune. They alleged her online searches included "perfect crime" and "stimulant drugs, lethal amount," and she obtained drugs from a dealer.

Sudo was the only person with Nozaki at the time he ingested the drugs, prosecutors said, arguing that it was unlikely that he killed himself given that he had planned a memorial service for his beloved pet dog and scheduled a doctor's appointment in the days after his death.

Following Thursday's ruling, the Wakayama District Public Prosecutors Office said in a statement that it will examine the ruling and respond after consulting with higher prosecutors.

The ruling said that neither the possibility she would inherit Nozaki's fortune nor the web searches were sufficient to presume intention to kill or that she was planning a murder.

In denying the charges, Sudo said she was asked by Nozaki to buy the drugs for him. Her defense claimed it was possible Nozaki ingested the drugs himself.

"If there is only suspicious evidence and there are doubts about concluding that someone is the culprit, they should be considered not guilty," her counsel said.

As the president of a liquor sales company and real estate business in Wakayama Prefecture, Nozaki is said to have had a personal worth of around 1.3 billion yen. Sudo married Nozaki, who was more than 50 years older than her, in February 2018.

Nozaki 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. Kishu is a historical name for the region in the prefecture where he lived.

Sudo is already serving a finalized sentence of three years and six months for defrauding a man of 29.8 million yen.