Third-year defensive tackle Josh Brent was arrested for intoxication manslaughter after the single-car accident that happened around 2:30 a.m. Saturday in suburban Dallas.
Jerry Brown, a linebacker who joined the practice squad this week, was pronounced dead at a local hospital.
Police say alcohol was a factor and that Brent lost control of his Mercedes at a high rate of speed.
"His vehicle touched or impacted the outside curb of the service road, causing his vehicle to flip at least one time," Irving police spokesman John Argumaniz said. "The vehicle ultimately came to rest on its top once it slid back in to the roadway."
Argumaniz says Brown was found unresponsive at the scene and pronounced dead at a hospital.
The police spokesman says officers conducted a field sobriety test on Brent and arrested him. The charge was upgraded after Brown was pronounced dead.
Brent was born here in California, in the Central Valley's town of Tulare. He grew up in Illinois. He's being held without bond and faces two to twenty years if convicted of felony intoxication manslaughter.
The Cowboys didn't immediately respond to an email request for comment.
(The Associated Press contributed to this report)