For months, a Tennessee Highway Patrol trooper assigned to the governor's protective detail was impaired on the job while taking painkillers, an internal investigation found.

His supervisors in the Executive Protection Unit knew he had on multiple occasions fallen asleep on duty, but they allowed the behavior to continue without taking disciplinary action.

A scathing internal memo from THP Col. Dereck Stewart shows the trooper's supervisors knew about his problem with prescription medication, and that his "pattern of behavior was allowed to continue for months without any knowledge of the THP command staff" higher in the agency, department records show.

Trooper Willie McCoy, formerly a sergeant assigned to Gov. Bill Haslam's protective detail at the governor's residence in Nashville, was demoted in December — more than five months after the department launched an investigation in July and 2½ weeks after the USA TODAY NETWORK - Tennessee first inspected his personnel files.

Documents related to the investigation weren't provided to the news organization when a reporter initially requested McCoy's files in November because of the ongoing investigation, according to the department.

The records were made available this week when the news organization contacted officials in the Department of Safety & Homeland Security after McCoy's demotion.

The records reference instances of McCoy falling asleep on duty in late 2017 but were only logged beginning in January 2018, THP Lt. Les Dolente, McCoy's supervisor, said in an internal investigation interview in July.

It is a crime in Tennessee to possess a handgun while under the influence of a controlled substance. McCoy was armed while on duty in the governor's protective detail.

On three separate occasions in January 2018, McCoy's colleagues reported him nodding off, snoring and mumbling in his sleep while on duty outside the governor's residence.

In April, two troopers working with McCoy and trained as drug recognition experts reported McCoy showed signs of impairment and that he had fallen asleep in the back seat of a car.

"Both indicated they believed Sergeant McCoy was under the influence of some type of narcotic," according to THP investigation documents.

His supervisors spoke with him but didn't take any disciplinary action.

"Some conversations occurred regarding sending Sergeant McCoy for a drug screen, but Lieutenant Dolente didn't know where they were in that process," the records state.

Despite several additional documented instances of colleagues reporting McCoy falling asleep on the job, he was not tested for drugs, according to the records.

McCoy's attorney has denied that the trooper was impaired on the job.

In an interview July 25, Dolente told investigators he saw McCoy fall asleep June 20 while taking inventory of portable radios while in a classroom at the THP training center.

Dolente again spoke with Capt. Tommy Fyke about possibly administering a drug test, records show.

"Lt. Dolente left to go out of the country shortly thereafter and nothing was done," a THP memo states.

According to the THP, Dolente had not requested any disciplinary action for McCoy and had not placed any documentation of McCoy falling asleep and possibly being impaired in his performance file.

In an unrelated case, Dolente was the THP official responsible for triggering an investigation last year into the violation of a confidentiality agreement by a trooper assigned to work protective details for then-gubernatorial candidates Karl Dean and Bill Lee.

June incident prompted first investigation into trooper's behavior

On June 22 at the governor's residence, another trooper returned to the post outside the house and found that McCoy "was very lethargic, his speech was slurred and his head was nodding," the records show.

McCoy had appeared fine at the start of his shift, the other trooper reported, but he soon after fell asleep.

The trooper "believed Sergeant McCoy was under the influence of some type of substance," he told his supervisors.

He had previously heard from colleagues about McCoy's rumored problem, records show.

"Is that the one who’s always high?” a colleague had asked that trooper once when discussing McCoy, he told investigators. He added that his colleague was previously in a dignitary protection class that McCoy was supposed to be instructing when McCoy fell asleep, the records show.

Maj. Michael Hamilton and Fyke responded to the governor's residence on June 22 and decided to take McCoy home that night. While Hamilton had contacted human resources to find out where McCoy could be taken for a blood test, he ultimately decided not to require one.

'A self-destructive and perilous path' without intervention

Multiple supervisors and co-workers of McCoy said that, based on their observations of McCoy, there were times he was so impaired he was unable to perform his basic job functions, the records show.

No actions were taken or blood tests administered.

"The protection of the governor and the first family’s residence is a core function of the department and specifically the EPU," Stewart wrote. "On (June 22), this core function was not fulfilled, which could have potentially led to significant issues for the entire department.

"The culpable liability of Lieutenant Les Dolente as the direct supervisor for Sergeant McCoy is noteworthy in this case," Stewart continued.

"In this instance, Sergeant McCoy was allowed to continue down a self-destructive and perilous path without any worthwhile intervention from his supervision."

Stewart also criticized Fyke's failure to inform Hamilton, who in June had supervised the protection detail for less than a month, that McCoy had a history of falling asleep on duty.

"The decision to not have a reasonable suspicion blood screen conducted not only gives the appearance of impropriety, but also hindered the investigation of the overall incident," Stewart wrote.

According to THP's General Orders policy, employees are not permitted to report for duty under the influence of any prescribed drug that impairs their ability to perform their duties.

It is also a neglect of duty, based on department policy, for a supervisor to fail to take appropriate action when he or she knows about an employee violating policy, procedures, directives or law.

Dolente was placed on a two-day suspension in connection with the investigation, while Hamilton received an oral warning, according to a Dec. 6 memo from Stewart to Commissioner David Purkey. No disciplinary action was listed for Fyke in Stewart's memo about the investigation.

Through spokeswoman Megan Buell, the Department of Safety & Homeland Security declined to answer additional questions or allow a reporter to speak with Stewart about the case.

Attorney says trooper is appealing demotion

McCoy's attorney, Paul Tennison, denied that McCoy had showed up for work under the influence of medication.

The pain medication he was on — the name of which has been redacted in THP files — was prescribed to McCoy by doctors for a 2016 on-duty crash he was involved in, according to departmental files and Tennison.

"He has never been addicted to the pain medication, as far as I understand," Tennison said in an interview.

"At all times during this process where he was alleged to have fallen asleep, he was on prescription pain medication properly prescribed to him, which was deemed necessary by a doctor to treat his work-related car crash."

McCoy is in the process of appealing his demotion, Tennison said, and has been "conducting therapy with licensed professionals since the June incident."

In a statement Tuesday, Haslam said he has "not gotten involved in THP personnel decisions, including those involving members of the Executive Protection Unit."

"Crissy and I are grateful for the service and protection provided to us by the executive security team and have great respect for their dedication and professionalism," Haslam said.

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Reach Natalie Allison at nallison@tennessean.com. Follow her on Twitter at @natalie_allison.