Ever since Augustus Standingrock and Tiffanie Pierce were charged with murder last year after two bodies were found dismembered and partially dissolved in chemicals in the basement of Pierce’s home, the open question has been why.

In court filings earlier this month, prosecutors revealed what they think motivated Standingrock, saying he believed one of the victims, Jackson Wiles, had abused a young girl close to Standingrock.

In the motion, prosecutors ask a judge to allow them to reference a prior violent conviction for Standingrock when he goes to trial for the deaths of Wiles, 24, and Marilyn Pickett, 15. That trial currently is set for November.

While a person's prior criminal history often is excluded during trial, prosecutors may include it if they can convince a judge that there is a clear link between an old case and a new one.

In the request, prosecutors say Standingrock attacked his mother’s new boyfriend with a crowbar in 2013 for the same reason they believe he killed Wiles last summer: a belief that the boyfriend and Wiles had both "harmed" the same young girl.

Standingrock's attorney wrote in his own filing that the prosecution contends that harm included sexual abuse in both cases.

But in his response, filed last week, one of Standingrock’s attorneys — Nick Brooke — said prosecutors have no evidence to show that was the motive in his client’s 2013 case, and told a judge it shouldn’t be allowed to be discussed at trial.

In 2013, Standingrock pleaded guilty to assault with a weapon, after being accused of attacking his mother's boyfriend with a crowbar while the man was sleeping.

Police reports do not mention any allegations that Standingrock was motivated by a belief that the man had harmed a girl. They include only that Standingrock and the man had been in a different fight the week before and that the man had recently told Standingrock, who was “couch surfing” at his mother’s home, that he wasn’t welcome to stay there anymore.

That's what spurred the 2013 assault, Brooke wrote. His response contends that prosecutors now are retroactively attempting to assign a new motive because of a recorded jail phone call between Standingrock and his mother in December.

In the call, Standingrock discussed media coverage of the 2013 case, saying it made the victim “sound like a good guy.” He went on to ask his mother “Did (a young girl) ever tell you what (the man) did to her?”

Standingrock’s mother appears to acknowledge what he’s talking about, but quickly ends the conversation.

Brooke’s response said evidence from the 2017 homicide investigation revealed that Wiles may have raped the same girl. But that despite the prosecution’s contention that her abuse was the motivation in both the 2013 and 2017 cases, no evidence conclusively supports that, he wrote. Brooke added that the recorded phone call from December doesn’t say what Standingrock believed had happened between his mother’s boyfriend and the girl.

“The crimes at issue are too dissimilar and share no distinctive characteristics, the State is simply pointing to violence by the Defendant and asserting they are joined by a previously unknown motive,” Brooke wrote.

Even if retired District Court Judge James Wheelis — who was brought in to oversee Standingrock’s case — does decide that 2013 case shares enough detail with the current homicide charges, Brooke said it should still be excluded at trial as overly prejudicial to his client.

Instead of relying on evidence presented to them, a jury will be swayed far more by the knowledge that Standingrock has a criminal history, his attorney said.

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“Countless studies demonstrate that jurors give greater weight to evidence of misconduct and dishonesty than to favorable evidence,” he wrote. “Introducing the 2013 case brings little to the State’s present case, but will have a dramatic impact on the Defendant’s chances at trial.”

Prosecutors will be able to file a reply brief on the issue, which could eventually lead, if necessary, to oral arguments at a hearing in front of Wheelis.


Standingrock and Pierce are each charged with two counts of deliberate homicide in the deaths of Wiles and Pickett.

Earlier this year, prosecutors also charged Pierce with attempted homicide and assault with a weapon after accusing her of breaking into a home and repeatedly stabbing a woman in Missoula weeks before Wiles and Pickett were killed.

While various court documents indicate Standingrock is believed to have been with Pierce during that July 2017 home invasion, he has not been charged.

Pierce was originally set to stand trial in September on both the charges from Wiles' and Pickett’s deaths as well as the home invasion. But after a hearing in the spring, a judge ruled that the cases would be separated.

The September trial is still on the calendar for the homicide charges, although earlier this week Pierce’s attorneys moved to delay that trial, a request a judge has yet to rule on.

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Law and Justice Reporter

Crime reporter for the Missoulian.