Fort Worth serial killing suspect indicted on fourth murder charge
A North Texas man charged with murdering and dismembering three people and burning their bodies in a dumpster last year has been indicted in a fourth death.
Jason Alan Thornburg, 41, faces charges of murder and arson, first-degree felonies punishable by up to life in prison, in the death of 61-year-old Mark Jewell, according to a Friday news release from the Tarrant County Criminal District Attorney’s Office.
Thornburg was separately indicted last year on capital murder charges in the deaths of 42-year-old David Lueras, 34-year-old Lauren Phillips and 33-year-old Maricruz Mathis. Their bodies were found dismembered and burning in a Fort Worth dumpster in the 3100 block of Bonnie Drive on Sept. 22, 2021. Before he was arrested in their deaths, police said, Thornburg admitted to slaying Jewell, who was his roommate. Authorities said Thornburg set fire to their home after killing Jewell in May.
Police had previously connected Thornburg to the May 21 death of Jewell, but concluded that they did not have probable cause to arrest him until after the September killings, Fort Worth police homicide unit Sgt. Joe Loughman has said.
Jewell died of thermal and blast injuries in a house in the 4500 block of Valentine Street, according to the Tarrant County Medical Examiner’s Office. The medical examiner originally listed the manner of death as undetermined but has since updated it to homicide.
Thornburg told police he sliced Jewell’s throat and started the fire by uncapping a natural gas line and lighting a candle in the bedroom, according to an affidavit supporting an arrest warrant in the Bonnie Drive case.
Firefighters found Jewell’s body in the bedroom were the fire originated, according to a Fort Worth Fire Department report.
Loughman said in 2021 it was the interest in Thornburg as a suspect in the death of Jewell that helped detectives narrow down a list of vehicle owners to identify him as a suspect in the deaths of Lureas, Phillips and Mathis.
Connecting Jewell’s murder to the triple homicide
Detectives began with about 7,000 Jeep Grand Cherokees that were manufactured between 2005 and 2010 whose registered owners live in Tarrant or Dallas counties. The make, model and year range came from a vehicle that detectives saw on a video surveillance recording at the Bonnie Drive scene.
Thornburg drove a Jeep Grand Cherokee that matched that description.
Police have said that Thornburg told detectives that he killed Lueras, Phillips and Mathis over five days in mid-September at Mid City Inn in Euless. Thornburg said that he strangled Phillips. To kill Lueras and Mathis, Thornburg said that he used a Milwaukee straight blade knife to cut their throats, police have said.
Confessing to five killings
Thornburg told investigators before he was arrested in the triple homicide that he had in-depth knowledge of the Bible and was being called by God to commit human sacrifices, police said in September 2021. That’s why, he told police, he killed first his girlfriend in 2017, then Jewell in May 2021 followed by Lueras, Phillips and Mathis in a span of days.
His girlfriend’s name was redacted in an arrest warrant, but her family identified her as Tanya Begay of Gallup, New Mexico.
Relatives of Begay told the Star-Telegram that they knew something bad had happened to the mother of two children.
“We thought maybe he had sold her for prostitution,” said Sheryl Tsosie of Gallup, New Mexico, in a telephone interview. She called Begay her “sister,” even though she was her cousin’s sister. “We didn’t want to believe he had killed her.”
Thornburg has not been charged in Begay’s death. Her body has not been found.
Mental illness examination
On Oct. 10, Mental Health Magistrate Judge Nelda Cacciotti ordered a mental health or intellectual and developmental expert to interview Thornburg to see if he has a disability. The order also asked for information about whether he received treatment recommendations or services in the past.
She said there was reasonable cause to believe Thornburg has a mental illness or intellectual disability. All of the indictments came down after that order.
This story contains information from the Star-Telegram archives.
This story was originally published February 18, 2022 at 3:45 PM.