HOUSTON — The Texas Alcoholic Beverage Commission has joined the investigation of a traffic wreck where a Houston woman and her baby were killed to find out how a 20-year-old Galveston County woman charged with intoxicated manslaughter in the case obtained the alcohol she drank.

Harris County prosecutors say evidence shows Veronica Rivas of Bacliff, who was under the legal drinking age of 21, was served at an establishment Feb. 28. Her speeding SUV later slammed into a car on an Interstate 45 service road, killing 36-year-old Shayla Joseph and her infant son.

Authorities say preliminary tests show Rivas, who is free on bond, had a blood-alcohol content of 0.21. The Texas legal limit is 0.08.

The place where Rivas was served could be fined or have its liquor license suspended.