February 19 (UPI) – State and local authorities said Monday they are still searching for missing 11-year-old Texas girl Audrii Cunningham, indicating that a suspect currently in custody on another charge is uncooperating.

That suspect, identified over the weekend as Don Steven McDougal, 42, has been given “multiple opportunities to cooperate and we continue to hope he will cooperate in this case,” Lt. Craig Cummings of the Texas Department of Public Safety told reporters in Livingston, Texas.

Cummings asked the public’s help in obtaining video of a section of Farm to Market Road 3126 in rural Polk County between 6:30 a.m. and 8 a.m. Thursday, when Audrii was last seen waiting for a school bus.

The girl was dropped off at the bus stop but did not make it on board, according to police. Her family reported her missing at 5:30 p.m. that same day, and an Amber Alert was issued.

The reward offered by Polk County Crime Stoppers for information leading to Audrii’s whereabouts was increased to $10,000 on Monday, officials said.

McDougal was identified as a “person of interest” in the case on Saturday after he was arrested and booked into jail on a charge of aggravated assault with a deadly weapon. His dark blue Chevrolet Suburban was also seized as evidence in the case.

Cummings said McDougal lived in a mobile home behind Audrii’s house and he had “a relationship with the family” that included occasionally dropping the girl off at the bus stop or even driving her to school.

Investors reported discovering a small backpack believed to belong to a child near Lake Livingston Dam.

Polk County Sheriff Byron Lyons said he was convinced the backpack belonged to Audrii and said investigators believe McDougal was the last person to see the girl.

Audrii is described as being 4’1″ tall and weighing approximately 75 pounds. She has blonde hair and blue eyes. When last seen, she was wearing a black hoodie with white lettering, a camouflage backpack, black pants, and black high-top tennis shoes.

Anyone with information about the case is asked to call the Polk County Sheriff’s Office at 936-327-6810 or 911. Tips can also be submitted through the iWatchTexas app.