(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.

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 that police said was involved in the disappearance. McDougal was arrested Friday by the Polk County Sheriff’s Office on an unrelated charge of aggravated assault.

Polk County Crime Stoppers is offering a $7,000 reward for information leading to the arrest and prosecution of those responsible for Cunningham’s disappearance.