The Kyoto District Court on Wednesday overturned the acquittal of a 50-year-old chief internist at a Kyoto hospital on charges of poisoning seven colleagues in 1998.
The court instead sentenced Hiroshi Ishida to 16 months in prison for putting sodium azide, a dangerous chemical, in a heated thermos in the hospital's staff room.
The same court had acquitted him in February 2003, citing lack of proof he was the perpetrator.
He stood trial there again, however, after the Osaka High Court nullified the acquittal in August 2004 on appeal by prosecutors and sent the case back to the district court for review.
Ishida appealed that court decision but was turned down by the Supreme Court in January 2005.
According to the indictment, Ishida poisoned the water heater in a staff room at the Utano Hospital at around 8:40 a.m. Oct. 28, 1998. Seven doctors who drank green tea made with the water became ill.
The prosecutors alleged Ishida held a grudge against the hospital chief, who was allegedly trying to dismantle Ishida's section.