A third suspect has been charged in connection with the murder of 19-year-old Bryson May during a December home invasion in Frazee.

Cash Christofer Mathieu, age 17 of Perham, faces two felony counts: first-degree aggravated robbery and aiding an offender to avoid arrest-harbor/conceal. 

Mathieu appeared in Becker County District Court on Monday, May 4. He waived juvenile proceedings and acknowledged a criminal case file will be established in adult court.

According to the court file, Becker County deputies responded to a report of shots fired at 701 Ash Avenue West at 2:30 a.m., on Saturday, Dec. 20, 2025. 

Arriving deputies located May and found him with gunshot wounds to his chest and head. May was transported to Essentia St. Mary’s, where he later died. 

According to previous reports, Arthur Campbell, 21, of Frazee, and Kayne Mackner, 16, of Detroit Lakes, forced their way into the home armed with guns, demanding money and property. Witnesses told investigators the group drove from Hawley to collect a debt, but went to the wrong house.

Mackner accepted a plea deal in February agreeing to be charged as an adult. He is facing second-degree murder charges and a maximum 35-year sentence. 

Campbell also faces a second-degree murder charge, along with second-degree assault, and soliciting a juvenile to commit a criminal act. Both men will be back in court on Tuesday, May 19.

According to court documents, Mathieu drove the men to Frazee, but remained in the vehicle. 

Campbell and Mackner entered the home. After hearing gunshots, Mathieu said he was preparing to leave when the duo ran out of the home back to the vehicle shouting “Go!”

Minutes later, Otter Tail County deputies stopped the vehicle on U.S. Highway 10 near Perham.

Further investigation revealed Mathieu allegedly set up the victim to deliver marijuana cartridges to the location. A call from the jail allegedly captured one of the suspects stating Mathieu was “just being a puppeteer, pulling the strings.”

Bail was set at $100,000 by Becker County Judge Gretchen D. Thilmony; bail options were set at $200,000 without conditions, or $100,000 cash or non-cash bond with conditions.

Mathieu will be in court again on Monday, June 1.