The president of a union representing Houston ISD support staff faces an aggravated theft charge after district police said he forged payroll deduction forms several years ago, causing nearly 100 employees to unknowingly lose out on about $72,350 in salary.

Hector Mireles, who has led Texas Support Personnel Employees Local 1 for about a decade, was arrested last week on a single felony charge. HISD investigators said the improper payroll deductions occurred during the 2015-16 and 2016-17 school years.

Mireles said Tuesday that he believes district officials are engaging in “union busting 101,” adding that the allegations initially were investigated years ago and did not result in criminal charges.

Police said the district’s internal auditor staff discovered several forged signatures on the payroll deduction forms, leading them to contact additional employees. Ultimately, 96 staff members told auditors that signatures attributed to them on the forms were not theirs, according to an arrest report.

Investigators determined amounts ranging from about $150 to $2,360 were deducted from the employees’ paychecks over two school years, the arrest report said. HISD police did not document the employees’ job titles at the time of the illegal deductions, but many of the victims now work as food service attendants, custodians and plant operators, recent payroll records show.

Mireles told HISD’s auditing staff that he and two other union representatives would visit campuses to recruit potential members, according to the arrest report. The HISD police arrest affidavit said the district’s internal auditors concluded Mireles forged the signatures, though document does not cite evidence proving Mireles was the culprit.

Mireles said he suspects HISD officials used the investigation as a way to reduce his union’s membership.

“I think when they did the audit, they convinced the employees that if you want out of the union, sign this sworn affidavit,” Mireles said. “There are so many folks that I suspect have a hidden agenda to try to get my organization out. I think they’re trying to ruin my name and my organization and our reputation.”

Mireles did not immediately provide a copy of the audit Tuesday. The document does not appear on the district’s website, which includes dozens of published audits dating back to 2015, and is not included in the public court file.

The HISD police affidavit states the criminal case stemmed from a police department captain providing a copy of the audit to a detective in January. The affidavit does not say when HISD’s audit staff completed the inquiry.

Texas Support Personnel Employees Local 1 members has about 750 members, Mireles said. Another union for HISD employees, Houston Educational Support Personnel, is the district’s largest for non-classroom staff with about 1,000 members.

Mireles formed TSPE Local 1 in 2009 about the same time that the Service Employees International Union revoked the charter of Local 100, which organized some HISD support staff.

jacob.carpenter@chron.com