Bus Driver Reports Dangerous Drunk Driver on I-90 in Montana

Missoula, MT (KGVO-AM News) - On October 23, 2026, at approximately 9:33 p.m., a Montana Highway Patrol trooper was notified of a possible drunk driver heading eastbound on Interstate 90 from Mineral County. The trooper contacted the complainant, a bus driver for Jefferson Bus Lines. The bus driver said a silver van was driving erratically, failing to maintain its lane, and traveling at inconsistent speeds. The bus driver said the driving behavior was so poor and that he called 911 because he thought the driver of the van was impaired.  

Around 9:46 p.m., he said the van was traveling right behind the bus at mile marker 82. Another trooper arrived in the area and observed the bus and van. The trooper observed the van actively passing the bus on the left. The van made an abrupt, unsafe lane change and cut off the bus. The van then took the Frenchtown exit.  

The trooper initiated a traffic stop. Prior to the van stopping, it failed to come to a complete stop at the stop sign on the off-ramp, turned right without using a turn signal, and failed to come to a complete stop at a stop sign at an intersection. The van finally parked at the gas station lot at Frenchie’s Super Stop.  

Signs of Impairment: A Closer Look

The trooper saw a female stumble as she exited the driver’s seat and moved into the rear of the van. The trooper contacted the female, who was identified as 47-year-old Karmen Prieto. The trooper asked Prieto why she was driving erratically. Prieto said that she “was not driving.” 

While speaking with Prieto, the trooper smelled the strong odor of alcohol coming from her. Prieto’s eyes were watery and bloodshot, and her speech was slurred. Prieto denied drinking any alcoholic beverages. 

Prieto was asked to perform the Standardized Field Sobriety Tests, but refused. Prieto was read implied consent, but refused. The trooper arrested Prieto. The trooper determined that Prieto’s license was not valid, and she also failed to have insurance. The trooper applied for and was granted a search warrant for Prieto’s blood. Prieto was transported to St. Patrick Hospital, where a blood sample was taken. Prieto was then transported to the Missoula County Detention Facility. 

READ MORE: Missoula News - Crime Reports

According to court documents, Prieto has four prior DUI convictions. She is currently being charged with felony DUI, failure to carry proof of insurance, and driving without a valid driver's license. Her bond was set at $50,000. 

The information in this article was obtained from sources that are publicly viewable.