A teenager sentenced last week to 10 years in prison for the strangulation murder of a Spokane woman is accused of assaulting another jail inmate Tuesday night.

Deputies say Matthew T. Shope, 19, attacked Joshua J. Mulvey, 26, in the Spokane County Jail just before 7 p.m., according to court documents filed today.

Mulvey (right), who’s being held on theft charges related to an alleged cross-country Craigslist rip off, suffered a fractured bone in his face and briefly lost consciousness, jail deputies said. He was treated at a Spokane hospital, according to court documents.

Shope appeared in Superior Court today on one count of second-degree assault.

Shope was sentenced April 20 to 134 months in prison after pleading guilty to second-degree murder for the Oct. 6, 2008, strangulation death of 28-year-old Jennifer L. Siria. His accomplice, Michael A. Quinones, 29, was sentenced to 25 years in prison March 25 after pleading guilty to first-degree murder.

Last fall, investigators say Shope wrote letters to the estranged wife of jail inmate David E. Epley after he and Epley grew close in jail.

Matthew T. Shope told police everything. He led them to the victim’s body, described her murder in detail and, ultimately, gave detectives a solid case against her killer.

But it’s what Shope did - and didn’t do - before his arrest that earned him more than a decade in prison under a sentence imposed Tuesday in Spokane County Superior Court.

“He was not the instigator of the incident,” said Deputy Prosecutor John Love. “However, he did not attempt to stop the incident.”

Shope pleaded guilty to second-degree murder for the Oct. 6, 2008, strangulation death of 28-year-old Jennifer L. Siria and was sentenced to 134 months in prison.

His accomplice, Michael A. Quinones, 29, was sentenced to 25 years in prison March 25 after pleading guilty to first-degree murder.

“I should have done something,” Shope said today through tears. “I was a coward in the situation and didn’t take action to stop it and I feel terrible for the family.”

Siria’s mother, Patricia, said Shope is an example of “what every parent fears for their child, that their bad choices will take them to a place they’ll never be able to overcome.”

“Why didn’t he run out and pound on doors and call for help?” she said. “I hope he wishes now that he had.”

Quinones and Shope gave Siria $20 to let them stay in her apartment at 537 E. Hawthorne Road but demanded the money back when they decided the leave, which led to Siria’s murder.

Shope feared he would be Quinones’s next victim, defense lawyer Mark Hannibal said. Shope helped Quinones clean the apartment, later telling police “it’s amazing how well you can clean when you’re threatened with your life,” Hannibal said.

A Spokane County Sheriff’s deputy picked Shope and Quinones up near the scene and released Quinones not knowing of the murder. But Shope refused to get out of the car and told the deputy he had an arrest warrant. Not finding one, the deputy drove Shope to Daybreak rehab, where the boy told employees “he had been involved in something that could send him to prison for a long time,” according to court documents.

Had it not been for Shope, “the killer would have gotten away with his crime,” Hannibal said. Hannibal asked Moreno to impose an exceptional low sentence of 114 months (the high-end sentence for first-degree manslaughter), but the judge declined.

“I just simply can’t justify it based on the loss of a life in this case,” she said. “I know that you feel badly. I know you are very remorseful for what you did and didn’t do….(but) the devastation that you caused with your codefendant cannot be ignored.”

Past coverage:

Drifter sent to prison for brutal slaying

Second suspect charged in murder

Police: Accused killer wrote rape suspect’s alleged victim