Authorities are investigating after a man said he found the body of an infant in a freezer while cleaning out his mother’s St. Louis apartment after she died.

Adam Smith told the St. Louis Post-Dispatch that he made the discovery when he opened a box Sunday that his mom had kept in her freezer for decades, bringing it along with her throughout various moves. He says he was going through his mom’s belongings after she died July 21 at the age of 68 from lung cancer.

Police said in a news release Monday only that the infant was found inside a residence and that the death is being investigated as “suspicious” pending an autopsy. Police declined further comment.

Smith says he has provided police a DNA sample.