Court records obtained by Action 4 News show that fatal chase all started because the suspect was not wearing his seat belt.
Hector Guadalupe Ramirez, Jr. remains in custody at the Hidalgo County Jail without bond.
The 18-year-old Roma man is accused of leading a Texas Department of Public Safety (DPS) state trooper on a fatal chase on Monday afternoon.
A probable cause affidavit obtained by Action 4 News show that DPS Sgt. Enrique Chavez was in an unmarked unit.
The DPS sergeant allegedly saw Ramirez driving a blue pickup truck while not wearing a seat belt north of Mission.
Ramirez refused to stop and ran a red light off Western Road and FM 2221 causing a four-car accident.
Six people, including four children, were killed in that accident.
The trooper states as Action 4 News first reported that he was in an unmarked DPS unit but equipped with a flashing blue emergency lights and an audible siren.
According to the affidavit, the troopers dash cam records the entire chase but authorities have not released the video.
Ramirez was injured but released from the hospital on Thursday and charged with murder.
Records show that the truck Ramirez was driving during the chase was stolen.
The Roma teen had been arrested weeks earlier for stealing another vehicle but was out on bond at the time of the chase.