The Yokohama District Court has sentenced an American man to 18 months in prison for throwing his mistress into the sea off Miura, Kanagawa Prefecture, last July.
Prosecutors had demanded a 30-month prison term for Gregory Gumo, 41, on the charge of disposing of 42-year-old Mariko Akitaya's body. Police arrested him on suspicion of murder but prosecutors decided last month not to indict him on the charge.
Gumo said during the trial that he was scared his wife at the time would find out about his affair with the temp worker from Tokyo.
Presiding Judge Shigeyuki Fukasawa said in the ruling Wednesday that the defendant thought only of self-preservation and such a selfish motive "left little room for leniency."
According to the ruling, Gumo threw Akitaya into the sea around July 28 last year, believing she was dead, even though chemical substances in her system may have meant she was merely unconscious. The ruling determined that she drowned.
However, Gumo's defense claimed Gumo was not guilty of the charge of abandoning a corpse, arguing the victim was alive when she was dumped at sea.
The court concluded, however, that Gumo assumed he was disposing of her body and she is believed to have died as she sank.