MILTON, Pa. — Investigators hope tests on a three-ton hunk of concrete will soon solve the 1989 disappearance of a young mother, by determining whether her remains were fed through a wood chipper and then entombed in the basement of a Pennsylvania duplex.

Sunbury Police Chief Tim Miller announced earlier this month that preliminary results showed the concrete contained wood chips, and he’s waiting to see if they also hold the remains of Barbara Elizabeth Miller.

A forensic pathologist is “dissecting the walls, so to speak, piece by piece, hammer-and-chisel type, looking for the smallest of clues,” Miller, no relation to Barbara Miller, said last week. He called it “mere speculation if a wood chipper was or wasn’t used. Obviously the presence of wood chips in a concrete wall is highly suspicious.”

An affidavit used to obtain a search warrant for the Milton home disclosed that investigators believe the woman may have been killed by her ex-boyfriend, a onetime Sunbury policeman named Joseph Walter “Mike” Egan.

Egan “is and has been the lead suspect in this case since 1989,” the chief wrote in the affidavit.

Egan, a Northumberland resident who trims trees for a living, on Friday flatly denied he had anything to do with Barbara Miller’s disappearance.

“They’re way off base,” Egan said, then promised to have his lawyer provide additional comment later in the day. He declined to name his attorney, and no one called back.