HARRISVILLE, Pa. (AP) – A forensic anthropologist and a team of students dug for the bodies of two missing New Hampshire children who were murdered by their father, but came up empty.

Dennis Dirkmaat, of Mercyhurst College in Erie, said he was called Saturday after two cadaver-sniffing dogs signalled the possible presence of human remains at a site in Barkeyville. The dogs, a pair of German shepherds, were being handled by searchers from the Pine Township and Grove City volunteer fire departments.

Dirkmaat and his students excavated a 5-foot by 4-foot site off Interstate 80 for about two hours, but found nothing, he said.

“We investigated the location where the dogs gave the signal and we didn’t find anything,” Dirkmaat told the New Hampshire Sunday News. “There was no indication of a burial ground. We dug into the ground 2 or 3 feet. We did a forensic archeological investigation and determined nothing was there.”

The missing children are Sarah Gehring, 14, and her brother Philip, 11, who were murdered two years ago by their father, Manuel Gehring.

After he was captured in California, Manuel Gehring told investigators he killed the children in his van in New Hampshire, then buried them somewhere along a 700-mile stretch of Interstate 80 between Pennsylvania and Iowa as he fled cross-country in his van.

Despite an intensive search, the bodies were never recovered. Gehring apparently tried to help in the search, but was unable to pinpoint the spot where he buried the children. He committed suicide in jail last year while awaiting trial.

The children’s mother, Teresa Knight of Hillsboro, N.H., traveled cross-country earlier this summer to re-start the search. Volunteers had been out searching in Barkeyville because it is near where officials said Gehring bought a shovel and pick axe. The area also contains possible landmarks described by Gehring.

A dispatcher at the Pennsylvania State Police’s Franklin barracks said police responded to the site after the volunteer searchers notified them of a possible find.

Barkeyville is a small town located about 50 miles north of Pittsburgh.