On April 13, 2016, the Texas Rangers confirmed an investigation into the alleged misuse of state funds by Commissioner Miller. The investigation centered around two state-funded trips Miller took in February 2015 for non-work-related reasons. Assistant District Attorney Susan Oswalt announced in September 2016 that no charges would be filed against the commissioner. In a memo to the Texas Department of Public Safety, Oswalt cited difficulty to prove criminal intent, the relatively low cost of the trips, Miller's reimbursement to the state, and the media exposure of the case for the decision.