(NewsNation) — Authorities have identified a 42-year-old man as a person of interest in the disappearance of an 11-year-old Texas girl who’s been missing since last week.

Audrii Cunningham was supposed to catch a bus near her residence in Polk County to go to school Thursday but never showed up. A small backpack was found Friday near Lake Livingston Dam northeast of Houston, and now a massive search effort is underway in that area.

Cunningham is described as having blond hair and blue eyes. The Amber Alert issued for her says she’s four feet, 1 inch tall.

The Texas Department of Public Safety named Don Steven McDougal, 42, as a person of interest and released a photo of his dark blue 2003 Chevrolet Suburban.

McDougal was arrested Friday by the Polk County Sheriff’s Office on an unrelated charge of aggravated assault.

Lt. Craig Cummings, spokesperson for the Texas Department of Public Safety in Southeast Texas, said at a news conference Monday that McDougal, who lives in a camper behind the residence where Cunningham lives with her father and grandparents, is a friend of the family’s.

McDougal, who had been dropping Cunningham off at the bus stop, was the last person to see the 11-year-old, Polk County Sheriff Byron Lyons said. He added that McDougal has been talking to investigators.

Although McDougal has previous child enticement charges, Cummings said he was not required to register as a sex offender.

“I’m hoping and praying that (Cunningham is) still alive,” Lyons told reporters.

While McDougal is the police’s main person of interest at this point, Lyons stressed they are not ruling out anyone else.

Polk County Crime Stoppers is now offering a $10,000 reward for information leading to the arrest and prosecution of those responsible for Cunningham’s disappearance.

People can contact the Sheriff’s Office at 936-327-6810 or the Polk County Crime Stoppers line at 936-327-7867 to submit tips.