Incumbent Taylor County Sheriff Les Bruce made a surprise announcement at the KTXS/Reporter-News runoff debate Tuesday night.
Bruce provided KTXS with the paperwork to prove it Wednesday.
The signed letter from his doctor said Bruce had passed the drug test.
The letter, dated May 16, said Bruce tested negative for the following substances: alcohol, amphetamine/methamphetamine, barbiturates, benzodiazepines, cannabinoids, cocaine, opiates and phencyclidine (PCP).
Whether Bruce would submit to a drug test became a contentious issue in the sheriff's race after an audience member at a public debate, leading up to the Republican primary election, questioned him.
The issue was again raised by another candidate, Art Casarez, who is no longer in the race.
KTXS wanted to know why Bruce revisited the issue at the Tuesday debate.
"I wanted to answer this question for the final time and get to the points of who has the experience and the knowledge and the ability to lead this agency as it needs to be lead to protect and to serve this community," Bruce told KTXS Wednesday.
He said he was disappointed the drug test became such a big issue during the campaign.
"It was the red herring of all red herrings," he said. "It was the most negative thing I'd ever witnessed in any election process."
Bruce said he is just now revealing his test results because he did not want to answer the earlier challenge he did not respect.
"I did not accept or submit to this drug test to answer any challenge from any political bantering," he said.
Bruce said he submitted to the drug test just 13 days before the Republican primary election in May.
The KTXS/Reporter-News runoff debate will air on KTXS at 6:30 p.m. Wednesday.
The runoff election between Bruce and Ricky Bishop is Tuesday, July 31.