PORTLAND, N.Y. (WIVB) – Two sets of human skeletal remains were found in a wooded area in the Town of Portland over the past three days, according to the Chautauqua County Sheriff’s Office.

Authorities told News 4 that both sets of remains — one discovered Sunday and another found in a subsequent search Monday — were found less than 20 yards from each other near the Rails to Trails entrance off Woleben Road, about 25 minutes southwest of Dunkirk.

However, authorities do not yet know if the skeletal remains are connected. One set appeared to have been in the ground much longer than the other, they said.

“We don’t believe that there is a serial killer,” Sheriff Jim Quattrone told News 4’s Chris Horvatits. “We’re not sure if it’s a coincidence or if this is related.”

Quattrone said a human skull was discovered Sunday. The ensuing excavation revealed skeletal remains of a female that had been in a shallow grave.

As a search for evidence was underway Monday, officers found a second set of remains, Quattrone said. This set of remains was mostly bones, and there was not an immediate indication of the age or gender, he said.

Police will continue trying to match the first, older set of remains to missing persons cases in the area.

“We have DNA from Patricia Laemmerhirt, who has been missing since 1976 from Westfield, which is just about ten miles from here,” Quattrone said. “Based on the forensic anthropologist, we are thinking that it’s probably in the ’70s that the first set of remains was located.”

Quattrone said the department also has dental records of Corrie Anderson, who went missing in Chautauqua County in 2008, and Lori Ceci Bova, who went missing in 1997.

But as for the second set of remains, which police believe were placed at their present location within the past year, Quattrone says they don’t have any recent missing persons locally who might be a match.

Both sets of remains were transferred to Mercyhurst Anthropology Lab in Erie, Pa. for further analysis.

This story has been updated.