The man who chopped testicles off four patients at a nursing home was mentally handicapped, local authorities in northeast China's Heilongjiang Province said Friday.

The case has illustrated poor management at some of China's nursing homes, which are troubled by insufficient funding and personnel despite rising demand from an aging population.

Wang, 46, allegedly tied up four patients and cut off their genitals with a blunt razor on Tuesday afternoon. He had drunk alcohol and was "looking for excitement and venting his discontent," said a statement by the government of Qinggang County, where the nursing home is located. He is now under police custody.

Two victims, 53 and 80, lost one testicle each, and another 60-year-old lost both. Two of them were bedridden in the institution, while the third is mentally handicapped. The fourth victim, who lost both his testicles, was not discovered until Thursday when police carried out a thorough inspection of the nursing home.

"I yelled, but no one paid attention," one victim told Xinhua.

He said Wang was in charge of distributing food at the facility and might have been annoyed by their leftovers.

The public facility where the tragedy happened is home to 165 people, all either impoverished rural elders or mentally handicapped. Xinhua reporters visiting the site found the rooms crowded and fetid. Many patients have not bathed for months. One said theft and beatings were regular activities at the facility.

Seven local officials, including a township government head, are being investigated following the incident.