Cottonwood Heights police investigated alleged thefts from their fire stations and obtained drug histories for several employees.
A detective found that Jones had obtained a large number of prescriptions for several different controlled substances from pharmacies, including hydrocodone and carisoprodol, which are pain relievers, and zolpidem, a sleep aid, according to the charges.
The prescriptions had been issued by three doctors, at least two of whom did not know Jones was receiving prescribed drugs from other physicians.
The detective interviewed Jones, and he initially said he took Celebrex and Lortab also pain relievers only as needed and infrequently. After he was confronted about his prescription drug history, Jones acknowledged taking pain medication three times a day, the charges add.
Investigators suspect Jones has been getting the prescriptions from May 2012 until last month.
UFA Chief Michael Jensen said Friday that the charges filed against Jones are not related to UFA's initial investigation into missing drug supplies. That investigation is ongoing, Jensen said.
The chief didn't go into details about the discrepancies in question because the investigation is ongoing, but said that they came to light "a few weeks ago," and likely lasted anywhere between a few days and a week.
"The high likelihood is unfortunately we have a bad egg," he said. "We want whoever did this found, and we're not going to tolerate it."
Jensen also emphasized that no patient care was compromised because the missing supplies.
Meanwhile, all of UFA's 637 employees are being looked at, and the department has re-emphasized its policies for handling controlled substances in its medical services. Jensen said that all paramedics are expected to review their medical supplies with the next employee coming on shift before clocking out, and that records are kept whenever drugs are used on patients throughout the day.
Jensen added that Jones who has been a county fire employee for 24 years was a good employee, and that no one perceived that he had a drug-abuse problem.
"I've never once seen him where I've believed he's been impaired," Jensen said. "Otherwise we have policies where we'd send him for drug tests immediately."
Jones has been placed on paid administrative leave while the case works its way through the court system, Jensen said. The UFA board will meet in two weeks, when it will be decided whether his payment will be suspended during his leave.
"We hope that if he does have a problem that he gets help, and we'll help him," Jensen said. "One thing about the fire service is we're a big family, and when you have a brother in trouble, you put your arm around them. Sometimes it's got to be tough love, but you want them to get better."
Jones, who lives in Bluffdale, has no prior criminal history, according to a search of Utah court records.
He was promoted in January from a battalion chief to the position of assistant chief, according to a UFA board agenda notice.
Jones was expected to surrender at the Salt Lake County jail for booking sometime Friday night, according to Jensen.
Bail has been set at $25,000.