The medical examiner's office said a 57-year-old man died last summer at the Milwaukee County Mental Health Complex due to complications of obesity and sleep apnea.
Paul Haugan was found dead at the complex July 28. The Milwaukee Journal Sentinel reported the medical examiner said Haugan also had cardiovascular disease. He weighed 375 pounds.
A federal inspector's report said Haugan had difficulty breathing and had been wearing an oxygen mask the day before he died. But he broke the mask while yanking it from his face.
According to the report, a nurse told investigators she didn't place a new mask on Haugan because he was sleeping.
The Mental Health Complex was cited by state and federal health officials. The state has approved the county's plan to correct procedural shortcomings.