SALT LAKE CITY — The death of a Utah doctor imprisoned for drugging his beauty queen wife and leaving her to die in a bathtub has been ruled a suicide.

Utah police released a report Friday on the April death of Martin MacNeill, who was convicted of murdering his beauty-queen wife Michele in a 2013 trial that became a national true-crime cable TV obsession.

The report says the 60-year-old MacNeill was found unresponsive April 9 near a prison greenhouse where he worked, in a spot where cameras couldn’t record him.

Police say there were no signs of a struggle.

Inmates told investigators that MacNeill likely killed himself because he lost an appeal. His lawyer has said MacNeill previously attempted suicide.