MERIDIAN —     The Arkansas State Police have fired a trooper accused of illegally confiscating a gun and dumping marijuana found during a traffic stop involving running back Michael Dyer, a former MVP of the national championship game who is now without a team.

    A termination letter from state police commander Col. J.R. Howard released Thursday listed several actions by Cpl. Royce Denney during the March 10 traffic stop that suggested he was ‘‘unable to conform to the standards of professionalism’’ expected of a trooper. Denney has appealed and his attorney, Jeff Rosenweig, declined comment

    The letter cites Denney for failing ‘‘to conform to law and (using) poor judgment’’ by confiscating without legal justification a gun found during the traffic stop of a car driven by Dyer, not long after the former Auburn star joined Arkansas State and coach Gus Malzahn. The letter says the trooper disposed of potential evidence by dumping the alleged marijuana at the roadside and improperly turned off the video recorder in his cruiser during the top.

    Audio and some video from the 58-minute stop was recorded and revealed that Denney spoke at length with Dyer about how he should handle getting in trouble.

    ‘‘What if I talk to Gus Malzahn, or however you say his name?’’ Denney asked. ‘‘I really don’t want to tell him about this because of the NCAA crap. I know there’s a lot of stuff that goes on behind closed doors between coaches and players. I’m still in a predicament, even if I talk to coach.’’

    Denney scolded Dyer for allegedly having a gun, saying: ‘‘You don’t need it. If you think it makes you look cool, you’re stupid.’’

    ‘‘It pisses me off that someone of your stature and your ability does this kind of stupid (expletive),’’ Denney said. The trooper asked Dyer if he wanted him to hold onto the gun, and Dyer said he did.

    ‘‘I didn’t say keep it,’’ Denney responded. ‘‘Maybe we can get together some other time, and you can have it back after me and coach talk.’’

    The termination letter says Denney had been disciplined three months earlier for failing to conform to the law and using poor judgment during a separate traffic stop.

    ‘‘Your conduct leaves me with no other choice than to terminate your employment with the Arkansas State Police,’’ Howard wrote.

    Malzahn, who left Auburn to return to his home state and the school in Jonesboro, opened practice Thursday. Dyer, who had been suspended indefinitely by Auburn coach Gene Chizik after last season’s Chick-fil-A Bowl, had followed Malzahn to Arkansas State.

    Malzahn dismissed Dyer from the team last week after revelations about the traffic stop, in which Dyer was ticketed for going 96 mph in a 70 mph zone.

    A university spokesman said it wouldn’t be appropriate to weigh in on a police matter.

    ‘‘It’s a state police matter being handled separately from ASU and we’ll respect that the state police are handling it internally,’’ ASU spokesman Jerry Scott said.

    On the other side of the state, trooper Capt. Jeffrey Lance King was cited by the Arkansas Ethics Commission earlier this year after he asked the panel to look at whether he received improper gifts from the Arkansas football program.

    Former Arkansas coach Bobby Petrino summoned King after he wrecked a motorcycle last spring while riding with a female employee on the back. Athletic director Jeff Long fired Petrino on April 10, saying Petrino had a conflict of interest by hiring Jessica Dorrell as a football program coordinator without disclosing they had an affair.

    State police looked at the relationship between Petrino and King, who accepted about $3,000 worth of tickets and Razorback gear while assigned to Petrino. The agency found no laws were broken.

    Dyer was a star at Little Rock Christian High School and was a top-rated recruit when Auburn landed him. He was the first Auburn tailback to rush for more than 1,000 yards in each of his first two seasons, including a 1,093-yard performance as a freshman that broke Bo Jackson’s school record of 892 yards set in 1982. Dyer rushed for 1,242 yards and 10 touchdowns last season.  He was also the offensive MVP as a freshman in Auburn’s victory over Oregon in the 2011 championship game.

    Dyer transferred to the Arkansas State in Jonesboro in January, and the school tried unsuccessfully to convince the NCAA to let him play in the coming season.