Missoula Deputy Stops Swerving Driver Who Admits to Using Drugs

Missoula, MT (KGVO-AM News) - On August 4, 2026, a Missoula County Sheriff’s Office Deputy was patrolling near Higgins Ave. The deputy observed a 2015 silver Chevy Impala jerk across two lanes of traffic and then jerk into the passing lane. The deputy observed the vehicle proceed through the intersection at Broadway, where it again jerked across two lanes before swerving into a parallel parking spot at Higgins and Front Street. The deputy saw the vehicle swerve into the curb.  

The deputy conducted a traffic stop, noting the driver opened his door and had to be instructed to stay in the vehicle. While approaching the vehicle, the deputy observed a clear, uncapped syringe in the back center console that appeared to contain a tan liquid. The deputy contacted the driver, who stated he did not have his identification but provided the name, Allen Grenfell.  

Grenfell appeared to be speaking rapidly and was making unusual statements throughout the entire contact. Grenfell stated he had used “molly,” which the deputy knew to be a street name for MDMA. The deputy Mirandized Grenfell, after which Grenfell admitted to injecting the drug approximately one hour prior to the stop and, when asked, stated he did not feel safe to drive. Grenfell stated he had additional drugs in the car, specifically a quarter zip in the center console. Grenfell also admitted to smoking marijuana that morning. 

Get our free mobile app

 The deputy observed Grenfell’s behavior to be jumpy and jittery, and based on the totality of his observations, the deputy believed Grenfell could possibly be impaired. The deputy instructed Grenfell on the Standardized Field Sobriety Tests (SFSTs), where he observed 3/18 indicators of impairment.  

Another deputy was also present and conducted further testing that he is trained to administer as an ARIDE-certified deputy. The deputy recognized multiple indicators of illegal drug use and signs of impairment.  

At the conclusion of the testing, the deputy read Grenfell the PAST Advisory, and Grenfell provided a PBT, which registered no alcohol. Grenfell was placed under arrest, during which time the deputy located a zip-top baggie of methamphetamine.  

READ MORE: Missoula News - Crime Reports

Grenfell was read the Implied Consent Advisory and refused to provide a blood test. The deputy applied for and was granted a search warrant for Grenfell’s blood. The blood draw was completed at St. Patrick Hospital, after which Grenfell completed a DRE exam with a Montana Highway Patrol trooper. The trooper observed indicators of a CNS stimulant.  

The deputy seized Grenfell’s vehicle and applied for a search warrant. During that search, the deputy located shards of meth in the back center console and two loaded syringes.  

Grenfell is currently being charged with felony criminal possession of dangerous drugs, criminal possession of drug paraphernalia, and DUI, first offense. 

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