An 82-year-old woman has been given a suspended sentence for killing her ex-husband who had dementia, after growing exhausted caring for him.

The Fukuoka District Court sentenced Taeko Baba on Tuesday to three years in prison, suspended for five years, over the death of the 82-year-old man, who drowned after she forced him to jump into the sea with her as part of a double-suicide attempt in the city of Fukuoka on Aug. 16.

Prosecutors had demanded a five-year prison term without suspension.

Baba began to care for the man after being asked by their child in February last year, a move that had been prompted by a traffic accident in which he was at fault. The request came despite the two's nearly 30-year estrangement, according to the court. They formally divorced in May last year.

But Baba grew exasperated with caring for the man, leading her to plan a double suicide, the court said.

Presiding Judge Koji Hiratsuka said the defendant was "in a state of diminished responsibility" at the time, adding that "the defendant had little help from other people and been struggling to prepare meals for him and arrange his residential care, which made her mental state worsen."

The judge said Baba had felt she had no other choice but to commit double suicide and "deserves some sympathy rather than a strong censure."