Ruperto Martinez Jr, 49, was arrested in 2016 and accused of exchanging nude pictures with a 14-year-old in Iowa.
The investigation began after the teen's mother discovered the images on her daughter's cell phone and alerted the sheriff's office in Iowa City, Iowa.
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Authorities in Iowa later contacted Houston's Internet Crime Against Children Task Force to assist with the Texas end of the investigation.
During the investigation, authorities learned the images were taken at Martinez's southeast Houston home and at Fire Station 93, where he worked.