But District Attorney John Champion would not say what led investigators to believe Jessica Chambers wasn't alone just before the fire burned her and the car Saturday night near a rural road near Courtland, Mississippi.
Chambers died Sunday. Since then, investigators have released very few details about the crime.
Chambers' funeral will be Saturday in Batesville, a small town in northwest Mississippi. The rewards for information about her case have grown to a total of $11,000.
Champion said investigators have talked to the person who called 911 and have cleared them from involvement in the crime. Investigators said they talked to Chambers' relatives and "there were no family issues," the prosecutor said.
Champion already has said investigators are treating the case as an arson, and an accelerant was used in the blaze. Three special agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives in Atlanta were in Courtland on Friday morning looking for clues at the crime scene.
The crime scene, next to an asphalt road with no dividing line, is nondescript except for the yellow police tape and the scorch marks on nearby trees and grass.
Questions abound about how the former high school cheerleader and her car ended up severely burned in this wooded area.
After obtaining warrants and cracking a password, police were able to access Chambers' phone records and are following up on leads, a prosecutor said Thursday.
Police are searching her data and text records after obtaining warrants Wednesday that compelled Google and her cell phone provider to give police access to her phone's content, Champion said. Investigators believe her phone will be "the key to everything," the prosecutor said. She received a call before she left her house, he said.
On Thursday, Champion spoke at a news conference, pleading for public help with the case and asking anyone with information, even if they think it's insignificant, to talk to police.
He said he didn't expect an arrest in the immediate future.
Champion said Wednesday that when firefighters arrived at the scene, Chambers approached one of them and spoke. Champion didn't divulge the teen's words but said, "It has certainly given us a lead we're following up on."
Chambers' older sister, Amanda Prince, said Jessica called their mother from a gas station and told her she would be home right after she cleaned her car.
The business, which Champion characterized as a rural mom-and-pop store, is about 2 miles from Chambers' home. It sells fried chicken, pizza and deli sandwiches, and there is a constant stream of people sharing rumors and random chatter about the killing that has rocked their area.
The gas station owner who helped her said nothing seemed out of sorts.
"She seemed normal," Ali Alsanai told CNN affiliate WREG
. "She didn't seem like something was going wrong, you know? She just seemed normal. She just pumped some gas, we had a talk and she left."
He said Thursday that one thing struck him as odd: Chambers pumped $14 worth of gas. She was a regular in the store, popping in every day or two, and she rarely pumped more than $5 in gas, he said.
"I asked her about it, and she said she was going somewhere," he said. "She was quiet that day, real quiet."
Employee Renna Tucker said Chambers was a fixture at the store. Everyone knew her, and she was "real friendly," the attendant said.
"Not one time have I ever heard her get loud, have a smart mouth. She was always smiling," she said.
A Facebook page titled Justice for Jessica
has drawn more than 97,000 likes, and that number was climbing rapidly Thursday. The page states it was created "to keep Jessica's name alive & out there."