The trial for a suspected serial killer begins Thursday morning in Tarrant County. 

Jason Thornburg is accused of killing and dismembering a man and two women in September 2021. Their bodies were found burning in a dumpster in Fort Worth.

In December 2021, Thornburg was indicted for the murders of David Lueras, Lauren Phillips and Maricruz Mathis. 

Police said the 44-year-old also confessed to murders of two other people years before –  his girlfriend, Tanya Begay, in Arizona in 2017 and Mark Jewell, his former roommate in May of 2021. Thornburg said it was all a "human sacrifice to God."

According to an affidavit, Thornburg said he has an in-depth knowledge of the Bible and believes he was called to commit human sacrifices. He even attended a leadership conference taught by one of his alleged victims. On a worksheet, he wrote that he wanted to be a missionary and said his greatest strength was "a sense of purpose, a sense of destiny that must be achieved."

In 2021, a Tarrant County judge ruled that there's reasonable cause to believe Thornburg has a mental illness or intellectual disability.

Prosecutors are seeking the death penalty for Thornburg.

Opening statements begin at 9 a.m. Thursday.