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Mark Johnston,
Benjamin Rettig is led from the witness stand after refusing to testify during day two of the trial of Martin Bond at the Fourth Judicial District Court in American Fork Thursday, Jan. 17, 2013. Bond is accused of killing former BYU professor Kay Mortensen in November 2009. Rettig is already serving a sentence for his participation in the same crime after pleading guilty.

AMERICAN FORK — Prosecutors have filed a new criminal charge against a man who admitted to killing a former BYU professor.

A single count of obstructing justice, a second-degree felony, was filed Tuesday against Benjamin Rettig, 25. Prosecutors charged him because they say he refused to testify against his co-defendant, as he had agreed to do in a plea agreement.

Rettig pleaded guilty to aggravated murder and aggravated kidnapping, first-degree felonies, in the Nov. 16, 2009, killing of Kay Mortensen, 70. The plea agreement removed the possibility of the death penalty in the case and Rettig was sentenced to concurrent sentences of 25 years to life in prison for the aggravated murder charge and 15 years to life in prison for the count of aggravated kidnapping.

Rettig also agreed to testify against his co-defendant, Martin Bond, as part of his plea agreement. In December 2012, investigators met with Rettig in prison and discussed his testimony at Bond's trial.

"Rettig agreed that he would appear and testify," the charges state.

But after he was called to testify and sworn in as a witness at Bond's trial on Jan. 17, Rettig refused to answer questions about the crime he committed with Martin Bond. The next day, he was again called to the stand and again refused to testify, despite being presented an immunity agreement and being ordered by the judge to do so, according to the charges.

Bond was convicted of aggravated murder, aggravated robbery, aggravated burglary and three counts of aggravated kidnapping, all first-degree felonies. He is now appealing the conviction.

Rettig is seeking to pursue an appeal of his sentence.

The two men were charged in connection with Mortensen's death at his Payson home. Bound with zip ties and with a gun to his head, he was made to kneel over his bathtub before his throat was slit.

Mortensen's son, Roger, and daughter-in-law, Pamela, were tied up at the home when they came to deliver a pie. They were originally charged in the killing until Bond's ex-wife tipped off investigators.

Rettig is scheduled to appear in court again for both cases on Sept. 3.

Email: emorgan@deseretnews.com

Twitter: DNewsCrimeTeam