BATESVILLE, Miss. >> A man charged with fatally burning a 19-year-old Mississippi woman acknowledged that he was with her on the evening she was set on fire after repeatedly denying it during interrogations, an investigator said today.

Mississippi Bureau of Investigation agent Tim Douglas testified in the trial of Quinton Tellis, who has pleaded not guilty to capital murder in the death of Jessica Chambers.

Prosecutors theorize that Tellis thought he suffocated Chambers during sex in her car in a driveway on the evening of Dec. 6, 2014. Tellis then drove Chambers’ car to a rural back road, ran to his sister’s house nearby, borrowed her car, stopped at his house to pick up a can of gasoline, and used the flammable fluid to set Chambers on fire, prosecutors said.

Firefighters found a smoldering Chambers walking near her burning car shortly after 8 p.m. in Courtland, Mississippi, about 50 miles (80 kilometers) south of Memphis, Tennessee. She had third-degree burns on most of her body when she died at a Memphis hospital.

Tellis, 29, was interrogated several times by law enforcement agents. Three of those intense interviews were videotaped and they were played to jurors Friday.

Tellis was interviewed twice in 2014 — on Dec. 10 and Dec. 18 — and he told investigators he had only seen Chambers the morning she was burned. Tellis said Chambers picked him up with a friend in her car, and Tellis rode around town with them as Chambers and her friend smoked marijuana.

Tellis said Chambers dropped him off at his house later that day and he didn’t see her again. He said he was in nearby Batesville buying a pre-paid debit card at the time she was burned and he had nothing to do with her killing.

Douglas interrogated Tellis three more times. During those interviews, Douglas and two other investigators confronted Tellis with cellphone records placing him with Chambers during the evening of Dec. 6 and video surveillance from a store across the street from his house showing vehicles entering and leaving his driveway.

Tellis first changed his story on Nov. 2, 2015. Tellis said that he actually drove to Batesville in a truck belonging to his friend “Big Mike” to meet Chambers in a parking lot shortly after 6 p.m. Tellis said he gave Chambers $10 and a bag of marijuana, and then jumped in her car as she went through a Taco Bell drive-thru.

Tellis said he left Chambers in her car and went back to Courtland to hang out with “Big Mike” and others.

In a Nov. 3 interview, Douglas again pressed Tellis.

“If you killed her, you were the last person who saw her alive,” the investigator told Tellis. “If you didn’t kill her, you’re the second-to-last one to see her alive.”

Tellis responded: “I don’t know who killed her.”

Douglas questioned Tellis one more time, on Jan. 27, 2016. Investigators had interviewed “Big Mike” and discovered he was in Nashville, Tennessee, on the day Chambers was burned. So Tellis could not have used his truck, the investigator said.

Tellis switched again, telling Douglas that Chambers had picked him up at his house about 5:30 p.m. and they drove to Batesville together to pick up the fast food. Cellphone records showed Tellis and Chambers were in the same spot until about 6:30 p.m.

Location reports on both their phones went silent for about an hour after that, investigators said.

In the interviews, Tellis doesn’t say he had sex with Chambers, though he did say he asked her for it that day. He also never acknowledges burning her.

Video surveillance presented in the interviews apparently shows a car stopping briefly at Tellis’ shed at 7:50 p.m. Chambers was found burning a short while later.