PHOENIX -- At least a dozen Phoenix civil servants -- police officers and firefighters -- are under investigation in a federal probe for alleged criminal use of anabolic steroids, CBS 5 Investigates has learned.

5 Investigates has learned the U.S. Drug Enforcement Administration began targeting doctors and clinics that have been writing bogus prescriptions for steroids.

The Phoenix police and fire departments have explicit written policies against the use of illegal anabolic steroids on the job.

Still, their departments are in the thick of criminal investigations that began almost two years ago with the Mesa Police Department and has now drawn the attention of the DEA.

"It's very concerning to use that our employees are illegally using these substances," said Kim Humphrey, Phoenix Police Department commander in charge of internal affairs.

Humphrey said they're aware of the possibility that more than a dozen officers may be involved in the federal case.

Police Learn Of Probe 3 Months Ago

Humphrey said they learned of the investigation three months ago after Phoenix police contacted the State Of Arizona Naturopathic Physicians Board Of Medical Examiners when one of their officers who tested positive in a random drug screen produced a prescription that didn't appear to be legitimate.

In the wake of a CBS 5 investigation last year, Phoenix police started randomly screening officers for steroids.

The Phoenix Fire Department just started pre-employment testing for firefighters.

CBS 5's investigations uncovered more than a dozen other firefighters, police and corrections officers across the Valley arrested, charged and convicted of felony steroids possession and distribution.

Those cases have uncovered serious reports of domestic violence, restraining orders and allegations of rage.

Phoenix police are now working with the Arizona Peace Officer Standards and Training Board in charge of certifying all arizona police officers to draft a statewide policy on illegal steroids.

Stay tuned to CBS 5 and KPHO.com for more exclusive details as the investigation unfolds in the coming days.