Salt Lake County sheriff's detectives were still trying to determine Thursday the origin of two human legs discovered Wednesday in a trash receptacle behind a grocery store.

A man rummaging through the dumpster behind Smith's Food King, 851 E. 45th South, found the legs, which were inside green plastic garbage bags, said Sheriff Pete Hayward."I'm sure he won't be jumping in any more dumpsters," Hayward said of the rummager.

The legs, which were cut cleanly just above the middle of the thigh, are believed to be those of an adult male, possibly Caucasian.

Each foot had a short stocking on it. Hayward said the amputations were "very smooth and seem to be almost surgical."

The flesh was "fresh and flexible," there was no sign of chemicals, and only a small sample of blood could be recovered, the sheriff said.

Capt. Bob Jack said all area hospitals had been contacted, and no body parts were unaccounted for. "I don't think it's a hospital amputation," he said, but added that he will wait for results from the medical examiner before making any conclusions.

An anthropologist is studying the legs to determine the sex and age of the person, he said. Meanwhile, the legs are at the medical examiner's office and might be sent to the FBI crime laboratory in Quantico, Va., for further analysis, Hayward said.

Deputies searched trash receptacles in a 10-block radius from the grocery store, looking for other evidence. The sheriff's office has not ruled out the possibility that someone is playing a prank with the legs.

"If it is, by damn, we're going to be charging someone with it," Hayward said.