(NewsNation) — Florida authorities are still searching for Madeline Soto, missing since Monday, and have arrested her mother’s boyfriend who they say is a “prime suspect.”

The 13-year-old girl was last seen around 8:30 a.m. on Monday morning after Stephen Sterns, her mother’s boyfriend, dropped her off near her middle school. Surveillance video showed her in the parking lot of Peace United Methodist Church, but she never made it to school.

Soto was reported missing on Monday after she wasn’t at the usual pick-up spot when her mother came to get her from school. Text messages on her phone showed she had told a friend she wanted to go live in the woods after she turned 13.

Authorities have conducted multiple searches for Soto with officers on foot and on horseback, using canine searches and going door-to-door with flyers about Soto’s disappearance.

Sterns was arrested after police discovered he had child sexual abuse materials on his phone during the course of the investigation. He has been charged with sexual battery and possession of child sexual abuse material but authorities have not said if those images are connected to the case.

Police said Sterns attempted to delete the images and videos from his phone and said they were both criminal and sexual in nature. Police also confirmed the events captured on the phone happened at Sterns’ Kissimmee, Florida, home.

While authorities have not connected those crimes to Soto’s disappearance, they did say Sterns is considered a prime suspect in the case as the search for Soto continues.

Soto is described as being a Caucasian girl with blonde hair and blue eyes, 5’1″ and 110 pounds. She was last seen wearing a green jacket, black shorts and white Crocs and has a mole on the left side of her nose and one on the right side of her chin.

Anyone with information about Soto’s disappearance should contact the Orange County Sheriff’s Office at 407-836-HELP.