TROUTDALE, Ore. - Authorities have arrested a man accused in the slaying of his elderly mother-in-law, who was found dead in her home earlier this month, police officials announced Tuesday.

William Henry Knepper Jr., 41, of Gresham, is facing aggravated murder charges in the death of 68-year-old Paula Jordan, pictured at right. It was the city's first murder since 1997.

Friends discovered the woman's body in her home at 1377 S.W. 10th St. when they came by to pick her up on June 6. An autopsy later determined she died of asphyxiation, police said.

Court papers that became public Tuesday revealed new information in the case, such as how investigators believe Jordan died.

Authorities believe she was hit so hard with a heavy glass lamp that the blow knocked out some of her teeth. The killer then smothered the woman with a pillow in her master bedroom, court papers indicate.

According to a court affidavit, police used high-tech tracking devices to find the woman's cell phone in a trash bin at a Beaverton apartment complex. In the same trash bin, investigators found blood that matched Knepper's on a latex glove as well as shoes that both Knepper and his wife identified as belonging to him, the court documents said.

Knepper works in Hillsboro, and his route would take him past those apartments, court documents said.

In addition, investigators found a photograph of Jordan in an outbuilding on Knepper's property that had apparently been used as a target on a dartboard.

The court documents did not discuss a possible motive for the slaying.

Knepper appeared in a Multnomah County courtroom Tuesday for his arraignment.