The Mississippi man accused of murdering Jessica Chambers believed he had suffocated the woman before lighting her on fire, prosecutors alleged during the first day of the high-profile trial.

The Clarion-Ledger reported that District Attorney John Champion accused Quinton Tellis, 29, of having sex with Chambers, 19, in her car on December 6, 2014, before he smothered her and set her on fire.

“I think he suffocated her,” Champion said. “And thought he had killed her and that he had to get her away from his house.”

Champion said that Tellis realized she was still alive and drove Chambers’ car to a backroad before dousing her and her vehicle with gasoline and lighting them on fire. He allegedly then got in his sisters’ car and fled the scene, according to the New York Daily News.

Prosecutors said Tellis went to a convenience store shortly thereafter and purchased a pre-paid debit card to create an alibi for himself.

First responder Cole Haley, the former chief of the Courtland Volunteer Fire Department, broke down in court when recalling his time with the dying woman.

“She had her arms out, saying, ‘Help me, help me, help me,'” Haley testified. “Her hair was fried like it had been stuck in a light socket. Her face was black, and her body was severely burned.”

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In a written statement, Haley claimed Chambers said in her final moments that “Eric” had done this to her. On the stand, however, he explained he was confused when he made he made his original report, according to USA Today.

During opening statements, defense attorney Darla Palmer noted that Chambers knew Tellis’ name yet said “Eric” was the culprit as she died.

“He insisted this is not something he would do,” Palmer said.

Champion acknowledged the discrepancy with Chambers’ last words but told the jury that the evidence they expect to present “will change your mind, I can promise you.”

Despite his claim, state attorneys haven’t revealed what they believe motivated Tellis to kill Chambers.

According to People, the 29-year-old has been indicted on murder charges in connection with the death of Meing-Chen Hsiao, 34, a Taiwanese graduate student in Louisiana. The outcome of the Chambers case will determine when he’ll be tried in Louisana.

Tellis faces life without the possibility of parole if convicted of killing Chambers.

[Featured Image: Handout/Ouachita Parish Sheriff]