Riverton Man Who Shot Friend In Head Gets New Trial Because Police Botched Miranda Rights

A man convicted of second-degree murder for mercy-killing his best friend can receive a new trial, after the Wyoming Supreme Court determined much of the mans confession invalid.

Clair McFarland

December 13, 20227 min read

Mario Mills 12 13 22
(Cowboy State Daily Staff)

Correction: The following story has been corrected to reflect that the detective on this case did not read the defendant his Miranda rights.

A man convicted of second-degree murder for mercy-killing his best friend can receive a new trial, after the Wyoming Supreme Court determined much of the man’s confession invalid.  

A trial jury convicted Mario Mills in March 2021, stemming from the shooting death of his friend Trevor Bartlett one year earlier. Both men were from Riverton.  

The Wyoming Supreme Court on Tuesday reversed Mills’ conviction and remanded his case back to Fremont County District Court for a new trial. The high court concluded that Riverton Police Officer James Donahue should have read Mills his Miranda rights at a crucial point in Mills’ police interview.

Suicide Argument 

Mills and Bartlett on the night of March 25, 2020, were in Mills’ garage drinking and playing cribbage, along with Mills’ wife. The wife went to bed and the two men remained in the garage.  

Bartlett, according to Mills’ police interview, repeatedly said he wanted to kill himself. Bartlett said he had a list of people he wanted to kill, then he wanted to kill himself, Mills had said. 

But Bartlett had reportedly told Mills he didn’t have the nerve to kill himself and asked Mills to do it for him.  

After arguing about it, Mills said he used a pistol in the garage to shoot Bartlett in the left side of his head.  

The Scene 

According to Mills’ wife’s police interview, Mills went upstairs and told his wife about the shooting. She went to the garage and confirmed that Bartlett was dead. 

She said she tried to call 911, but Mills asked her not to because he did not want to go to jail. 

They returned to the garage, she said, and tried to arrange the scene to make Bartlett’s death look like a suicide. They then changed their clothes and put the clothes they had been wearing in a bag, the order relates.  

Blood Spatter 

Mills’ wife at about 5 a.m. the next morning called 911, reporting she’d just found Bartlett dead in the garage and believed he’d shot himself, the order says.  

After the initial response, Detective Donahue arrived on scene around 6 a.m. and interviewed both husband and wife, who both said Mills had gone to bed that night and left Bartlett drinking in the garage alone.  

The stippling around Bartlett’s head wound was spread out rather than concentrated around the wound; there was no blood spatter or blowback on the gun – suggesting the gun was shot from a farther distance than likely during a suicide, the order states.  

The gun also had no impact marks, as would be expected had it fallen from Bartlett’s hand and hit the concrete floor 3 feet from his body.  

Donahue asked the Mills family if they would come to the police station to be interviewed. They agreed to come at 10 a.m. 

In The Night 

Donahue first interviewed the Mills’ daughter, a female child. The girl described waking at about 1 a.m. to the sounds of her mother and father upset and hearing a description of Bartlett being dead in the garage, which she found odd, the order states.  

Next Donahue interviewed Mills’ wife, who at first insisted Bartlett had committed suicide, but eventually described being woken by her husband, telling her he’d shot Bartlett.  

The Interview 

Donahue then interviewed Mills in a room of the police station with one door.  

Donahue did not tell Mills he was free to leave, though he did tell Mills at the beginning of the interview that Mills was not under arrest, the order says.  

Donahue started by congratulating Mills on how well-raised his daughter is and commending Mills for his military service. He then said he’d spoken to Mills’ wife and daughter, and added, “we’re in the business of truth,” telling Mills that men must be honest even when they’re afraid.  

‘Accusatory’ Questions 

Minutes later, Donahue said his purpose was not to ruin Mills’ life, disrupt his family or upend his work, but to provide an opportunity for him to free his mind and heart and discuss what happened, the order recounts.  

Mills said he couldn’t remember what had happened the night before.  

Donahue said he knew there was more, that Mills had had some very specific conversations and did some specific things, and that he – Donahue – knew all about it, the order says.  

Mills said he had the feeling Donahue was accusing him of having killed Bartlett.  

“We both know,” said Donahue eventually, “you didn’t just go upstairs and go to bed,” adding that Mills’ wife had wanted to call 911 in the night, the order says.  

“So you’re saying I shot Trevor?” asked Mills.  

“I’m asking you,” replied Donahue.  

Mills started to hyperventilate, the order says.  

“Right now, you’re seeing what happened,” said Donahue. 

“Oh sh**, I shot Trevor,” Mills said.  

Donahue asked how Mills had shot Bartlett.  

Mills kept hyperventilating.  

“It’s coming back to you,” said Donahue. “So what happened?” 

Mills then described the argument the men had had, the list of desired murder victims Bartlett reportedly had, his deliberations when he was trying to decide whether to shoot Bartlett, and Bartlett’s desire to die, the order relates.  

Confession Thrown Out – Mostly 

The jury should not have gotten to hear any of Mills’ confession following his first utterance of “I shot Trevor,” the state Supreme Court ruled in its order.  

After Mills confessed to killing his friend, Mills could reasonably have expected that he was not free to leave the police station, the court added.  

Had Donahue explained to Mills his Miranda rights in that moment, the rest of the confession would have been valid in court, but Donahue did not.

A confession alone doesn’t put a man under arrest or in a state of confinement, the court said. But all factors considered together – including Mills’ confession to a serious crime, the build-up of “accusatory” questions from Donahue and the nature of the police station room in which the interview occurred – indicate an environment of confinement.  

Though the now-suppressed portion of Mills’ interview can’t be presented as evidence at his second trial, if he pursues one, prosecutors still can use the contents of that portion to contradict Mills if he says anything inconsistent with it in court.

Second Degree 

Having ruled most of Mills’ confession invalid, the state Supreme Court still had to decide whether to send the case back to the trial court.  

It could only be done if the parts of the confession now invalid had harmed Mills at trial.  

The court found they had.  

Mills’ statements after “I shot Trevor” fit the crime neatly into the second-degree murder charge, rather than the voluntary manslaughter charge the jury also was offered, the high court wrote.  

The trial jury last year had the option to convict Mills on first-degree murder, second-degree murder or voluntary manslaughter. It chose second-degree murder, and the court sentenced Mills months later to between 20 and 25 years in prison.   

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Clair McFarland

Crime and Courts Reporter