A letter opener found in a priest's room was a "perfect fit" when inserted into a jaw wound suffered by a nun slain in 1980, an assistant coroner testified Tuesday at the priest's murder trial.

Also, the letter opener appeared to match punctures in an altar cloth that had been placed over the nun's body, another investigator told the jury.

The testimony came at the trial of the Rev. Gerald Robinson, 68, in the slaying of Sister Margaret Ann Pahl. She was stabbed to death and choked in a hospital chapel in 1980. Investigators have not disclosed a motive for the killing.

"We took the letter opener and inserted it. It was a perfect fit," Diane Scala-Barnett, an assistant Lucas County coroner, testified about a second autopsy done after the body was exhumed in 2004.

"Twenty-four years later, you could still see the stab wounds," she said as the priest sat impassively.

The first autopsy done on the day of the 71-year-old nun's slaying showed she died of 31 stab wounds to the face, neck and chest — including nine wounds that authorities have said were in the shape of an upside-down cross. There also was evidence that she had been strangled.

"It's a pretty unusual blade," Detective Terry Cousino said of the letter opener found in a desk drawer in Robinson's room near the chapel. The sword-like opener had a diamond-shaped cross-section.

Cousino said he went to great lengths to see if he could find a similar letter opener, even looking at Internet auction sites, but "never found one like this."

The letter opener also was consistent with punctures in the altar cloth, he said. He said mirror-image blood stains indicated the cloth had been folded in half over the nun's body.

The pattern of punctures indicated the killer may have used a template or guide, according to Cousino, who displayed a graphic showing a cross-shaped template fitting neatly between the linen punctures.

Josh Franks, a retired criminalist, testified that he removed a medallion from the letter opener and found a small speck that he tested. He said the test indicated the possible presence of blood, but the speck was too small to do a more conclusive test. No DNA tests were available at that time, he said.

Franks said the letter opener had no fingerprints or smudges.

"It was sumptuously clean. It appeared as if it had been polished. That was interesting," he said.