Hyogo police acknowledged Wednesday they failed to maintain an adequate vigil on a 64-year-old female murder suspect who was on a suicide watch but nonetheless managed to hang herself in her cell last month.
In their report on the apparent suicide, the prefectural force said suspect Miyoko Sumida made 22 remarks that could have been interpreted as suicidal, but authorities only were made aware of 11 of them. She had made the remarks to investigators, detention facility officials, other inmates and lawyers after she was placed in the cell in November.
The prefectural police said this failure to share all of her comments indicated their "sense of vigilance was insufficient," the report said, adding that officers may have dismissed the notion that she was suicidal based on her perceived characteristics and attitude.
Officers found Sumida dead in her cell with her clothes twisted around her neck on Dec. 12 and declared that she had strangled herself.
Sumida was a key suspect in a series of apparent slayings in the Hyogo city of Amagasaki.
The police found the corpses of six people known to her, including decomposed bodies under a house in Amagasaki, and Sumida was indicted for the murder of a 66-year-old woman whose body was found in November 2011 in a concrete-filled metal drum in a warehouse in the city.
She was served with a fresh arrest warrant in early December on suspicion of killing Jiro Hashimoto, 53, after his body, also in a concrete-filled drum, was pulled from a harbor in Okayama Prefecture.