(CNN) -- A social worker in Switzerland has confessed to sexually assaulting more than 100 disabled children and adults, authorities said Tuesday.
The 54-year-old man, who was not identified, said the assaults took place over a 28-year span in nine institutions where he worked as a therapist. He is from Argovie district in northern Switzerland, according to a statement from the regional public prosecutor of Bern-Mittelland and Bern cantonal police.
He has confessed that since 1982, he abused people while he was employed in homes and institutions for people with mental and physical disabilities in Switzerland and Germany, authorities said. Most of the facilities where the alleged incidents occurred are in Bern canton.
The man has since been interviewed more than 50 times since his arrest last April, and has been "very cooperative" in revealing "further information on similar cases," the statement said.
He had been investigated in 2003 in connection with the alleged sexual assault of a 13-year-old girl, but the case was dropped because of insufficient evidence, authorities said.
In all, the man confessed to sexually abusing 114 people -- all of whom were mentally disabled and some of whom also had physical disabilities -- who have been identified by canton police. The man also confessed to eight attempted sexual assaults, authorities said.
Most of the victims were male; 42 of the victims were older than 18, authorities said. One of the victims was 1 year old at the time of the alleged assault.
Police said the man told investigators that some of the abuses occurred several times on the same day. In 18 cases, the abuses were photographed or filmed. Investigators determined that no images or videos had been posted to the internet.
The statute of limitations has passed for most of the offenses, authorities said, but the man can be prosecuted for 33 cases.