The 66-year-old man confessed to keeping his mother's body in the basement of a property in the Innsbruck-Land region of western Austria after officers visited the house on Saturday, according to a police statement sent to CNN on Friday.
The 89-year-old woman is thought to have died in June 2020, police said, but the man kept her body in order to continue receiving her pension and care allowance.
Police said the man collected around €50,000 ($59,000) during the time he kept his mother's body in the basement.
An autopsy carried out on Wednesday did not reveal any signs that the woman's death was suspicious, the statement continued. The man is accused of benefit fraud and hiding a dead body.
The man said he froze his mother's body using ice packs to prevent any smell and wrapped her in bandages to soak up any bodily fluids, the AFP news agency reports.
"He covered his mother with cat litter and finally the corpse was mummified," Helmut Gufler, head of the police's social security fraud unit, said in an interview with public broadcaster ORF, according to AFP.
When the man's brother came to see their mother, he would tell him she was in the hospital. It was only when a new postman asked to see the recipient of the benefits he was delivering that the story started to unravel, the agency said.
The postman reported that the man had refused to let him see the mother, according to AFP, and authorities went to check the property.