She is facing a count of first-degree murder.
Wilson was visiting from California and staying with a friend. She was in Austin ahead of a race in Hico.
Court papers say the night of the murder, Wilson went for a swim at Deep Eddy Pool with Colin Strickland, another cyclist.
Then they went to Pool Burger before Strickland dropped her off back at her friend's house.
Documents say Strickland and Armstrong were in relationship before briefly ending it for a couple of weeks last year.
At that time, he was involved with Wilson.
An anonymous caller told police when Armstrong found out, she said she wanted to kill Wilson. Armstrong also told the caller she'd gotten a gun.
Armstrong's car was seen on surveillance video at Wilson's friend's home. Authorities are looking for a 2012 Black Jeep Cherokee with Texas license plate LDZ5608.
Wilson's friend later came home to find Wilson with multiple gunshot wounds.
FOX 7 Austin went to the address listed for Armstrong and Strickland, but there was no response. We also called Strickland, and it went to voicemail.
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These developments leave the cycling community in further mourning.
"It's so incredibly painful for such a tight-knit community, and people you've raced with, celebrated with, like, so many miles with, to be faced with this horrific tragedy. My reaction is just pain and heartbreaking," Alison Tetrick, Wilson's teammate and friend, said. "It's just, kind of stunned. Tragic. You just want to hug people you love at this point."
Anyone with information on Armstrong’s whereabouts is urged to contact the U.S. Marshals Service Communications Center at 1-800-336-0102 or submit a tip using the USMS Tips app.
Tips may also be sent to the Capital Area Crime Stoppers at 1-800-893-8477.