The Austin Police Department said Brenna Swindell was last seen with her ex-boyfriend Morgan Guidry on Thursday, Aug. 22, at Poodies Hilltop Bar in Spicewood, Texas, a 45-minute drive west of the state capital.
Guidry also had not been seen since, and police said their phones remain off.
Police describe Brenna Swindell as 5 feet 4 inches tall with tattoos on both arms. APD added that her vehicle is a 2022 Kia Carnival.
"Ms. Swindell has not been in usual contact with her family and friends. APD is concerned about her safety and immediate welfare," an Austin police statement read.
In an update Monday afternoon, APD said the Travis County Sheriff's Office is investigating the case. Anyone with information about Brenna Swindell is being asked to call 911 immediately or a tip line at 512-854-1444.
Greg Swindell, who retired in 2002 after 17 years in baseball, attended University of Texas at Austin and Sharpstown High School in Houston. He has yet to speak publicly about Brenna Swindell's disappearance.