Tuesday marked three weeks since she was reported missing from her Rogersville home after her mother said she left the girl with her three brothers, who the family says lost track of her.
She hasn’t been seen since.
"Agents and detectives follow up on tips as they are submitted," Tennessee Bureau of Investigation spokesperson Leslie Earhart said Tuesday. "To date, we've received nearly 840. We continue to urge anyone with information about Summer's disappearance to contact law enforcement directly at 1-800-TBI-FIND."
Authorities had previously asked the public not to submit rumors or speculation, but they also say that any credible detail, however small, could help break the case and find Summer’s whereabouts.
Investigators were also seeking a potential witness who was seen in a late 1990s maroon or red Toyota Tacoma with a full-sized ladder rack and white buckets in the bed.
"We want to stress that this individual is not a suspect, but is a potential witness who may have heard or seen something that may help us in our search for Summer," the TBI said in a statement.
Additionally, neighbors and other area residents and businesses were asked to review security and trail cameras for possible clues.
Summer is about 3 feet tall and weighs around 40 pounds. She was last seen wearing gray pants, a pink shirt and may have been barefoot. She has close-cropped blonde hair, possibly shorter than what appears in recent pictures, and blue eyes.
Investigators say the circumstances surrounding her disappearance have yet to be determined – but they said they were looking into "all possibilities."
Her parents, Don Wells and Candus Bly, both have criminal records in other states. Well’s most recent arrest came in October 2020, although a domestic assault charge was dropped, and he pleaded guilty to a firearms charge.
A criminal complaint from that incident alleges that deputies responded to the couple’s home and encountered Wells pulling up the driveway, reeking of alcohol and with a pistol in the glove box, which he was not allowed to possess.
Bly and the children were granted an order of protection, after she wrote that, "He drinks and throws things. I am afraid of being hurt. He is abusive physically and mentally toward me. I am afraid for my children and myself. My mother fears he is going to hurt her because she is staying in her camper on the property."
But she had it dropped less than a week later, court records show, and the two appear to have reconciled.
They told local media they believe that Summer was lured off their 11-acre rural property and taken.
"The investigation into the disappearance of Summer Wells remains active and ongoing," said Earhart, the TBI spokesperson. "In order to preserve the integrity of the investigation, we're not able to provide specifics beyond what we've already released publicly."
Wells and Bly have not responded to Fox News’ attempts to reach them for comment.