What happened to Audrii Cunningham, the missing Texas girl who ran away from home to go to school, and what do we know?

(CNN) — The only clue to the disappearance of 11-year-old Audrey Cunningham may be the red “Hello Kitty” bag she was supposed to take to school.

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Cunningham went missing after leaving her home to catch the school bus on the morning of Thursday, February 15, in Livingston, a small East Texas town about 70 miles northeast of Houston.

He reported that Audrey never boarded the bus Polk County Sheriff's Office. However, the agency said, “there may be a small backpack that is located near the Lake Livingston Dam.”

A man arrested in an unrelated aggravated assault case is now believed to be a “person of interest in the girl's disappearance,” the sheriff's office said. According to the sheriff of Polk County, Texas, the man was involved in the search for the girl on the day she went missing.

However, Cunningham's whereabouts now remain a mystery.

Audrey Cunningham. (Credit: Polk County Sheriff's Office)

Here's what we know about the case so far.

He never came to school that day

Audrey Cunningham was last seen around 7 a.m. Thursday near her home on Lakeside Drive, according to the Polk County Sheriff's Office.

According to the agency, “The house is located near Lake Livingston, one of the largest reservoirs in the state, covering more than 335 km. Texas Parks and Wildlife. “The lake is a reservoir for the Trinity River and supplies water to the city of Houston and other cities in East Texas,” the agency added.

According to the Sheriff's Office, “Audrey should have caught the school bus at her nearest stop. However, school officials informed the Sheriff's Office that the school bus did not pick up Audrey, nor did she show up at school.”

Audrey's family reported her missing after she did not return home from school. The search involved multiple agencies, including the Texas Rangers, Texas Department of Public Safety, Livingston Police Department, Texas State Guard and several local fire departments, the sheriff's office said.

Maybe they found his bag

This Friday, “a small backpack belonging to a juvenile was located near the Lake Livingston Dam,” according to the Polk County Sheriff's Office.

Earlier, authorities said, Audrey was carrying a bright red “Hello Kitty” bag.

However, the sheriff's office said the investigation is “active and ongoing.”

Authorities are searching for Audrey Cunningham, an 11-year-old Texas girl who went missing in Polk County on Thursday, February 15. (Credit: KHOU)

A person of interest joined the search for the girl. The sheriff believes he did it for “appearances.”

A family friend named by investigators as a person of interest in the disappearance of Audrey Cunningham participated in the search for the girl the day she disappeared, the Polk County, Texas, sheriff said.

“Some witnesses even said she was out in the community and knocking on doors… 'Have you seen her?' Sheriff Byron Lyons told CNN

Don Steven McDougall was arrested Friday in an unrelated case and has not been charged in connection with Cunningham's disappearance. The sheriff says that because McDougal was involved in the search, there is no reason to exempt him from Cunningham's investigation.

“To me, that indicates he's trying to make it look like he's not responsible for her disappearance, which is why he's participating in groups trying to find her,” Lyons said.

Asked if he believed the search effort was exonerating McDougal, Lyons replied: “No. No, I don't think so. I think he's our first person of interest.”

Lyons says McDougall and Audrey left the house and headed to the bus stop the day she disappeared. McDougal lives in a caravan owned by Audrey's family.

The 42-year-old man is “one of the persons of interest involved in the disappearance” and investigators believe his dark blue 2003 Chevrolet Suburban is involved, the sheriff's office said.

“This is what you see on television.”

Audrii Cunningham's mother, Cassie Matthews, said she always aches for the parents of missing children she hears about on the news.

“It's the kind of thing you see on television, and you can imagine what the family and the parents are going through.” Matthews told CNN affiliate KPRC.

Now he is one of those parents.

“There's no words to describe it. There's not even a feeling. It's a roller coaster. You're broken, you're angry, you're empty. Right now, I'm empty,” Matthews said.

“There are many opportunities ahead of him and he deserves every right to achieve them.”

Audrey is white, with blonde hair and blue eyes. He is about 1.2o meters tall and weighs 34 kilograms, the sheriff's office said. The woman was last seen wearing black pants, a black hoodie with white lettering and black high-top sneakers.

Anyone with information on this case is asked to immediately contact the Polk County Sheriff's Office at 936-327-6810 or Submit an anonymous complaint online.

CNN's Rosa Flores, Chris Boyd and Joe Sutton contributed to this report

This article has been updated