Rettig took the stand on Jan. 17 during Bond's trial, and began to answer basic questions, such as where he lived as a child. But when the questioning turned to the events that led to Mortensen's death on Nov. 16, 2009, Rettig refused to testify.
"I know everyone ... it was in the agreement to, and everyone expects me to, but I would feel more comfortable stopping right now," Rettig said in January.
On Tuesday, a new charge of obstruction of justice, a second-degree felony, was filed against Rettig.
According to a probable cause statement filed in 4th District Court, investigators met with Rettig at the Utah State Prison last December, and he agreed to testify. But after being put on the witness stand twice in two days during Bond's trial, he refused to testify, even after being ordered to by Judge Thomas Low.
Prosecutors allege that Rettig obstructed justice by "concealing unprivileged information," and pointed to a recent Utah Supreme Court decision saying Wade Garrett Maughan could be charged with obstruction of justice for refusing to testify against Glenn Howard Griffin during Griffin's 2008 murder trial in Box Elder County.
Rettig is also seeking to appeal his prison sentence. In April, Rettig asked Low to reinstate his appeal rights, according to court records, claiming that he was not advised of his right to appeal the sentence before the time limit for an appeal expired. He said in his handwritten motion that his previous bid to the Utah Court of Appeals was denied because it was filed too late, which he blamed on his attorney.
But Utah County Attorney Tim Taylor said in a written response that Rettig's rights were not violated since the plea-agreement documents that he signed on June 1, 2011, advised him that he had limited appeal rights and that any appeal had to be filed within 30 days. Taylor wrote that Rettig already received the most lenient sentencing possible for the crimes he pleaded guilty to, adding that it would not be rational to appeal the sentence.
Rettig will appear in court on Sept. 3, where both his appeal and the obstruction of justice charge will be discussed.
In January, a jury found Bond, 26, guilty of aggravated murder, three counts of aggravated kidnapping and one count each of aggravated burglary and aggravated robbery. Low sentenced Bond to life in prison without the possibility of parole.
According to court documents, Rettig and Bond broke into Mortensen's Payson Canyon home the night of Nov. 16, 2009, to steal the man's extensive gun collection. During the burglary, Rettig trained a handgun on Mortensen as Bond slashed the 70-year-old man's throat with a knife, prosecutors said.
Rettig also helped tie up Mortensen's son and daughter-in-law, Roger and Pamela Mortensen, who happened to come to the house during the burglary.
The couple spent roughly eight months in jail facing murder charges for the slaying before a tipster led police to Bond and Rettig.