Jurors will resume deliberations Wednesday after doing so for about three-and-a-half hours Tuesday.
Brent faces up to 20 years in prison if convicted.
Prosecutors accuse the former defensive tackle of drunkenly crashing his Mercedes in suburban Dallas after a night out in December 2012, killing his good friend and teammate Jerry Brown.
Brent's attorneys say he wasn't drunk and questioned the basis for the state's case, including blood testing and other evidence that suggested Brent may have had as many as 17 drinks on the night of the wreck.
Authorities say Brent's blood-alcohol level was more than twice the legal limit.