Ezekiel Gilbert shot Lenora Ivie Frago in the neck on Christmas Eve in 2009. Frago was left paralysed and died from complications seven months later.
Gilbert’s defence say his actions were justified because he was trying to retrieve stolen property.
They cited a Texas law which allows people to use deadly force to recover property during a nighttime theft, The San Antonio Express News reports.
According to Gilbert’s team, Frago refused to have sex and to return the money, claiming she had given it to her driver.
Upon his acquittal, Gilbert thanked God and told the court: “I sincerely regret the loss of the life of Ms Frago.
“I’ve been in a mental prison the past four years of my life. I have nightmares. If I see guns on TV where people are getting killed, I change the channel.”
ThinkProgress points out Texan law also authorises deadly force during “criminal mischief in the nighttime” and even to prevent someone who is fleeing immediately after a theft during the night or a burglary or robbery, so long as the individual “reasonably” thinks the property cannot be protected by other means.