Police in San Antonio say Israel Reyes, 23, shot Zachary Williamson, 41, in the face on April 6.
Police documents reviewed by KSAT-TV show Reyes claimed she fired in self-defense.
But detectives determined she and Williamson were together at an apartment for hours before the shooting.
Reyes and Williamson were the parents of an 8-month-old child.
Reyes was being held April 20 on $175,000 bond.
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