Former Hunt County Constable Anthony Dewayne Lewis called 911 Saturday night and admitted he had just shot two people, according to court documents obtained by News 8.
In the affidavit, Lewis also warned "he was armed and would not be taken alive by law enforcement."
Authorities said Lewis refused to drop his weapon when they confronted him following a three-county pursuit Saturday night.
Officers shot and wounded Lewis, but he was ultimately taken alive. Lewis is now at Parkland Hospital, where he is recovering from his wounds.
Lewis is charged with murder and attempted murder.
Police said Lewis opened fire Saturday night on his ex-girlfriend, Jessica Aguilar, and her companion, Francisco Delacruz, outside The Harbor shopping center in Rockwall.
Aguilar later died, and Delacruz is still recovering from his wounds.
Police said Lewis then led them on a chase that stretched all the way from Garland to Greenville. Eventually police managed to disable his vehicle, which led to the armed confrontation.
Family members said Aguilar had lately become increasingly worried that "something was going to happen." They said she had ended her two-year relationship with Lewis last summer, but that he was still pursuing her.
Aguilar will be buried in Garland on Friday, family members said.
Jaime Puente, the oldest of Aguilar's three children, said she had recently begun talking to an attorney about getting some sort of protective order against Lewis, but he did not know any specifics.
Rockwall County records show no history of protective orders associated with Aguilar or Lewis.