Indianapolis Colts assistant coach Robert Mathis was arrested Tuesday morning on a preliminary charge of operating a vehicle while intoxicated after police said he had shaky balance, appeared confused and nearly struck a street sign.

Mathis was pulled over shortly after midnight in a Carmel neighborhood south of 106th Street and east of Towne Road after a police officer said he saw the former defensive lineman travel the wrong way in the northbound lane of Windemere Boulevard, according to a police report. The officer also said Mathis failed to use a turn signal and nearly hit a street sign.

Mathis, who was driving a 2018 Chevrolet Silverado, told police he had two shots of Crown Royal whisky and took a “sleeping aid” at 10 p.m., according to the report.

A breath test showed Mathis was driving with a 0.052 percent blood-alcohol level. In Indiana a driver is presumed drunk at 0.08 percent.

An officer conducting a drug-use assessment said Mathis appeared under the influence of a CNS depressant, the report said. CNS depressants include drugs such as Valium and sleep medications such as Ambien. The specific drug was redacted in the police report.

The police report indicated that Mathis had slow speech and shaky balance and appeared lost and confused.

"That (blood-alcohol) reading combined with other factors led officers to believe he was impaired and not safe to operate a vehicle," Carmel Police Sgt. D.J. Schoeff told IndyStar.

When the officer asked for a driver’s license, Mathis handed him a large vehicle placard that comes with new vehicles, according to the report.

“Robert Mathis stated he was on his way home but had no idea where he was,” the officer wrote in the police report.

When Mathis was told to get out of the car, he dropped several items that had been in his lap and needed to lean against his SUV, according to police.

When Mathis was told to walk a straight line in a field sobriety test, he “stepped off the line, performed an incorrect turn, raised his arm more than 6 inches away from his body for balance, took an incorrect number of steps and did not touch heal to toe,” as required, the officer wrote.

IndyStar left a message with Mathis' attorney, Jennifer Lukemeyer, seeking comment.

John L. Tompkins, an Indianapolis defense attorney who specializes in drunken-driving cases, said a driver's failure to walk a straight line or perform other field sobriety tests may not be enough to prove intoxication, Tompkins said.

"Athletes with a history of injuries, bad knees, bad joints and the like often perform poorly on these tests," said Tompkins, who is not representing Mathis.

Mathis, 36, was booked into the Hamilton County Jail at 3:30 a.m. Tuesday on an initial misdemeanor charge of operating a vehicle while intoxicated, records show. He was released at 8:41 a.m. without posting bond.

An initial hearing was scheduled for Nov. 8.

Mathis was added to the Colts coaching staff as a pass rush consultant in September after working in an unofficial role for a few months. Mathis, a lifelong Colt, was drafted in 2003 and went on to rack up 123 sacks over 13 seasons.

Colts Senior Director of Communications Avis Roper issued a statement Tuesday.

“We are aware of the incident involving Robert Mathis last night," Roper said. "We are in the process of gathering more information and have no further comment at this time.”

More on Mathis:

Robert Mathis' one regret: He 'expected to win more than one ring in Indy'

The Colts can't get rid of Robert Mathis

3 visions of a Colts pass rusher: rookie, veteran, mentor

Call IndyStar reporter Vic Ryckaert at (317) 444-2701. Follow him on Twitter: @VicRyc.