An infant's skeleton found in a dead woman's suitcase was born at 35 weeks gestation, but authorities don't know its gender or how long it had been there.

There was no sign of trauma to the fetus, whose remains were found Saturday in Hempfield Township, said Westmoreland County chief deputy coroner Paul Cycak. The cause and manner of death will likely be ruled undetermined, he said.

The remains also will be examined by a forensic anthropologist at Mercyhurst College, state police said. It remains unclear when that examination will take place. Police said the investigation is ongoing.

Forensic pathologist Dr. Cyril Wecht used bone measurements and other techniques to determine the fetus' age, Cycak told the Pittsburgh Post-Gazette.

The fetus was wrapped in a "smock," its arms folded across its chest and its knees tucked into its chest in a fetal position, Cycak said.

State police said adult siblings cleaning out their elderly mother's house after she died in early December found the skeleton in an "old style" suitcase stored under the woman's bed. Cycak said the suitcase appeared to be from the 1950s.

The siblings did not recognize the suitcase as their mother's, but said clothes found inside belonged to her, Trooper Lisa Jobe said. Police did not immediately release the dead woman's name.

No charges have been filed. The coroner did not immediately return calls for comment from The Associated Press on Monday.

Hempfield Township is about 30 miles east of Pittsburgh.