A Florida man who is dating the mother of a missing 13-year-old was arrested on Wednesday for allegedly possessing child sexual abuse material on his phone.

Stephan Sterns, 37, the last person who saw missing 13-year-old Madeline Soto, was taken into custody on charges of sexual battery and possession of child sexual abuse material, the Orange County Sheriffs Office announced .

Soto was reported missing on Monday and was last seen with Sterns, who authorities said in an earlier press conference had dropped her off near her school. Sotos mom, Jenn Soto, discovered that evening, when she went to go pick her daughter up, that Madeline never made it to school that day.