A plea agreement he signed last month downgraded the charge to aggravated sexual assault of a child, capping his punishment at 15 years and allowing for deferred adjudication probation as a sentencing option.
Judge Philip Kazen sentenced Deleon, who was seeking probation, to the maximum prison time the deal allowed.
Deleon was two weeks shy of retirement from Brackenridge High School in May 2012 when allegations surfaced about the abuse of a girl who was not a student there.
According to court files, the girl told police that Deleon started touching her inappropriately when she was 10 and that it continued until she was 13, when she told authorities.
She came forward only after Deleon made it clear that his intention was to have sex with the girl when she was older and asked for her to give him a pair of her underwear, documents state.
Speaking on behalf of his client, defense attorney Rodolfo Orta told police that the girl made the false allegations after Deleon — who received a $110,000 lump sum retirement check — declined to buy the girl a Gucci purse, according to court files.
In a letter to the court, the girl wrote that her experiences with Deleon had traumatized her, leaving her with “horrible nightmares” and making her “afraid to be alone even with my father or brothers.”