A deputy taunted an autistic student. Now the boy’s dad is suing Pinellas schools and sheriff.

The father of an autistic student who was taunted and berated by a sheriff’s deputy in 2017 has sued both the school district and Sheriff’s Office in Pinellas County.

Derek Dowdey alleges in the suit that both agencies were negligent in their duties to protect his son, Evan Dowdey, during his interactions with a school resource officer at Osceola Middle School in Seminole. It says the boy has suffered mental and emotional trauma.

The officer, longtime Pinellas deputy Ural Darling, was fired soon after using what Sheriff Bob Gualtieri called “unacceptable” disciplinary tactics when Evan threw a book at a teacher.

RELATED: Pinellas school officer taunted, berated and threatened autistic student (w/video)

Darling suggested he would use handcuffs on Evan, who at the time was 13 but had the cognitive ability of a first-grader and the communication level of a kindergarten student, according to the sheriff.

Darling also told the boy that he would be sent away to a mental hospital for the rest of his life if he threw a book again.

Marge Aspell, a behavior specialist at the school, was present during the interaction between Evan and the deputy. At times, she joined Darling in the taunting, the sheriff said. She remains in the same position at Osceola, school district spokeswoman Lisa Wolf said Tuesday.

The school district declined to comment on the lawsuit. Sheriff Gualtieri said he was not aware of it and could not comment.

Meanwhile, Evan has continued to suffer emotional trauma from that day, said Dowdey’s attorney Michael Bird. He continues to fear law enforcement officers and authority figures.

“He’s had to seek counseling because of it, and his counselors … clearly are saying that this had a pretty dramatic impact on his socialization,” Bird said. “He has a general level of anxiety from all of it.”

Evan’s ability to interact with others was already strained by his autism. But it is “substantially worse” because of what happened at Osceola, the attorney added.

Bird said Aspell had a “moral and legal obligation” to stop Darling from berating the boy.

“She was literally sitting in the room while this happened,” he said. “I think it’s morally reprehensible if you’re a behavior specialist to … watch that happen in front of you without intervening.”

Records show Aspell received a letter of reprimand from the district’s Office of Professional Standards about five months after the incident, on Oct. 3, 2018.

She told district investigators that she called on Darling to meet with Evan because he had a “meltdown,” said the letter, written by professional standards administrator John J. Frank. Aspell went on to describe a hierarchy at the school that wrongly includes law enforcement in the discipline process.

“I find that the process you used to involve the SRO in disciplining a student was an example of poor judgement and exposed the student to harsh treatment by the SRO,” Frank wrote. “Your professional judgement should have alerted you to the fact that the SRO was being too harsh and aggressive with the student and led you to intervene.”

The suit asks for a jury trial and more than $15,000 each from the school district and Sheriff’s Office.

Contact Megan Reeves at mreeves@tampabay.com. Follow @mareevs.