American investigators say a 67-year-old man concealed his mother's decomposing body at their home in rural Wisconsin for years so he could continue to receive her monthly Social Security benefit cheques.

Deputies went to the house in Washburn County in June after a postal worker contacted authorities because mail had not been collected.

WQOW-TV reported on Wednesday that they found Michael Egan's body on a bedroom floor. He had been dead for more than a week.

Cadaver dogs later found the remains of his mother, Elizabeth, on a couch under rags, sleeping bags and plastic.

"It appears Elizabeth had been deceased for quite some time and that her son, Michael Egan, was mixing a solution and then soaking the rags and putting the rags on top of the body," according to police records.

Bank officials told authorities that Elizabeth's monthly Social Security cheque was directly deposited in the bank for years, including one for $US1,128 in June. Investigators believe that Michael Egan had been using her account for years.

Investigators said there was very little decay of the body because the towels had a solution on them that helped preserve it.

Authorities don't know how long Elizabeth Egan had been dead but say she was last seen in 2005 when she was 95 years old.