LA CROSSE, Wis. (AP) — An elderly woman whose body was kept in the freezer for four years while her son continued to collect her Social Security checks appeared to have died of natural causes, according to autopsy results released Wednesday.

Sheriff Mike Weissenberger said it appeared that the woman died of kidney and heart failure, but pathologists were still awaiting toxicology tests.

The body was found packed in 200 to 300 pounds of ice inside a chest-style freezer in the woman's basement Sunday after a 15-hour police standoff with her 52-year-old son, Philip Schuth, who was arrested on charges of shooting a neighbor.

Schuth told authorities that his mother died naturally in 2000 but that he was afraid he would be blamed.