The "The Haunting of Hill House" actor allegedly tried to use toilet water instead of a urine sample in the hopes of passing his blood-alcohol test.
According to the Tualatin Police Department report obtained by TMZ, he refused to complete his breathalyzer and field sobriety tests when pulled over in October, so he was taken to the station.
The 48-year-old was put in a holding cell and asked for a urine sample. Thomas requested to use the toilet, police say, and then attempted to swap the water for urine when the officer turned his back.
The report described the sample as "not warm, clear and filled to the brim," and said Thomas denied tampering with the sample.
In late October, the Tualatin Police Department in Oregon confirmed to Fox News that officers received a 911 call about a suspicious vehicle parked in a lane for travel. When police arrived at the scene, they found Thomas passed out behind the wheel of the motionless vehicle.
The officers reportedly had to wake him up. They quickly noticed signs of intoxication and promptly took him to Washington County Jail, where he was charged with a misdemeanor DUI, according to the department's public information officer, Jennifer Massey.
In November, he reportedly accepted a plea deal that will allow him to avoid jail time following his DUI arrest.
Thomas pleaded no contest to driving under the influence and reckless driving after he was arrested in Oregon on Oct. 21. Rather than serve any time, though, the star accepted a rather plea deal with some strings attached.
TMZ reported at the time that Thomas will enter a diversion program for one year in addition to paying a $500 fine. He’ll also have to attend a one-time victim impact panel, as well as have his vehicle outfitted with an ignition interlock device to prevent further incidents of driving under the influence.
Fox News' Tyler McCarthy contributed to this report.