Police began a full-fledged investigation Saturday over a number of suspicious deaths surrounding a Tottori Prefecture woman arrested over a fraud case with the possibility of building murder cases in mind.

The move comes after investigators discovered that a prefectural police officer, who was found hanged in February last year, was an acquaintance of the 35-year-old woman, bringing the number of deaths possibly linked to her to six.

Among the six, 57-year-old Hideki Maruyama, who was found dead in a river in October, had a scar on his face that indicated someone might have tried to press it against something, investigative sources said.

Sleep-inducing drugs and ingredients of a cold medicine were found in the bodies of Maruyama and two others.

Other men whose suspicious deaths were reported earlier this week are a 42-year-old Yomiuri Shimbun reporter who was run over by a train and killed in May 2004, and a 27-year-old company employee who drowned in August 2007 in the Sea of Japan along the coast of the prefecture.

The reporter had become acquainted with the woman as a customer of a bar in Tottori where she worked, while the company employee had lived with her for a period.

Suspicion also surrounds the deaths of Kazumi Taguchi, 58, who lived in an apartment in the same complex as the woman and died at his home in October shortly after becoming ill, and Kazumi Yabe, 47, a truck driver who was found in the ocean off Tottori in April.

All had been acquainted with or had financial troubles with the woman.