SALT LAKE CITY — A federal appeals court upheld the conviction of a Utah man for killing a Millard County sheriff's deputy with an assault rifle, a crime for which he had been acquitted in state court.

A U.S. District Court jury last year convicted Roberto Miramontes Roman of shooting Josie Greathouse Fox to death after a traffic stop in 2010. Jurors also found him found guilty of discharging a firearm in connection with a violent crime, three counts of possessing a firearm in the commission of a drug trafficking crime, and three counts of distributing methamphetamine.

A federal judge sentenced him to life in prison.

Roman argued in an appeal that the court erred in excluding evidence from his acquittal in state court. He also challenged the sufficiency of the evidence in his conviction for carrying a gun in a drug-trafficking crime.

The 10th Circuit Court of Appeals ruled Thursday that the evidence from the state trial wasn't material and its value was "substantially" outweighed by the risk of unfairly prejudicing the government, confusing the issues and misleading the jury.

The court also found there was enough evidence for a "rational" jury to find him guilty of carrying a gun in a drug crime.

In August of 2012, a jury in state court found Roman not guilty of aggravated murder but convicted him of tampering with evidence and possession of a dangerous weapon in connection with the deadly shooting.

The U.S. Attorney's Office then sought charges against Roman in federal court. A federal grand jury returned an 11-count indictment against Roman in 2013, including a charge of intentionally killing a local law enforcement officer engaged in the performance of official duties.

Defense lawyers argued that the new charges amounted to double jeopardy. A federal judge and a federal appeals court rejected those claims.