Officers found Stephen Broderick, 41, about 20 miles from the scene of Sunday's shooting, which prompted active shooter alerts and unnerved residents in the Texas capital at a time when the U.S. has been wracked in recent weeks by mass killings.
Sunday's shooting began in the afternoon when Austin police said they received multiple 911 calls about shots fired in the city's northwest area.
Authorities identified the victims as Amanda Broderick, 34, Stephen's former wife; Alyssa Marie Broderick, 17, Stephen's stepdaughter; and Willie Simmons III, 18, the teenager's boyfriend. Austin police said they were found lying near two vehicles following a collision at an apartment complex where Amanda Broderick and her former husband were meeting for a scheduled visit with their son, who they said was unharmed during the shooting.
As the investigation continued, detectives secured an arrest warrant for Stephen, who was taken into custody without incident just before sunrise Monday, on the outskirts of Austin, after officers received reports of a person matching the shooter's description, Manor Police Chief Ryan Phipps said. He said Stephen was walking down a rural road and carrying a loaded pistol in his waistband.
"I'm truly heartbroken that a former Travis County Sheriff's Office Deputy is the suspect in such a horrific incident," Travis County Sheriff Sally Hernandez said.
Broderick was being held without bail in Travis County jail. It was not immediately clear whether he had an attorney.
"I am incredibly grateful for all of the assistance provided by our law enforcement partners that came to our aid yesterday. This is a tragic incident that has deeply impacted our community, and I'm glad to report that the suspect has been taken into custody without incident, and with no additional loss of life. A special thank you to Special Agent in Charge Christopher Combs with the FBI for their strong support, as well as the citizen who spotted the suspect this morning that led to his capture," Interim Austin PD Chief Joseph Chacon said.
Prosecutors say Stephen lost his job as a sheriff's deputy last year after being arrested on charges of sexual assault of a child. Court records show that a protective order on behalf of Amanda, his ex-wife, and two children had been filed against Stephen following that arrest in June.
That order had required Stephen to surrender his firearms and wear an ankle monitor to track his whereabouts, according to Travis County prosecutors. Police did not say where Stephen got the weapon used in Sunday's shooting.
School officials in nearby Elgin, where Alyssa Broderick and Simmons had attended school, described them both as standout students and athletes. Broderick had been a member of the Elgin High School basketball team and enrolled in an early college program before she withdrew from the school district last October, said Jodi Duron, the school superintendent.
Simmons was a senior and football team captain who had been recently recruited to play at the University of North Texas next year.
Omasha Brantley, who coached both teenagers in Elgin, said they excelled both in and out of the classroom.
"She was an early college student, Willie was an A-B student," Brantley said. "Those were kids you would just go look for every day."
Austin police said the motive behind the shooting has not been determined and the case remains under investigation.
The Associated Press contributed to this report.
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