What started as a welfare check for 66-year-old Michael Maisner has turned into a death investigation, after human remains were found in his back yard fire pit.

Mercyhurst University's Forensic Science Department is helping out with the investigation.

"We were involved in the recovery and so what we try to do for all of these scenes is try to figure out what happened here," said Mercyhurst University Forensic Science Department chairman Dr. Dennis Dirkmaat. "When we respond to those, we document the scene very carefully. We note where everything is located."

State police say Maisner was last seen nearly three weeks ago and was reported missing last week.

According to PA State Police, the remains found in the fire bit were burned, making it difficult for them to identify.

"When we're dealing with fragments or an incomplete body then we have to go to other factors," said Dr. Dirkmaat. "Obviously these days, it's DNA."

Investigators say 35-year-old Marisa Rodriquez lived in Maisner's attic and stole his car, then drove to Chautauqua County, New York.

She has since been arrested and extradited back to Erie.

Police are still trying to determine whether she played any role in Maisner's disappearance.