Luis Manuel Casillas, a Houston mechanic and married dad of two young children, was fatally shot in the head after a heated argument with a client about a $500 repair bill that turned violent, the victim's family said in a statement.On Friday, December 23, 2022, Luis Manuel Casillas, 29, was shot in the head in the 7600 block of the North Freeway in Houston after he got into a dispute with a customer over a $500 repair bill. The money was reportedly expected to go toward buying presents for his kids.Houston Police@houstonpoliceNorth officers are at a shooting scene 7600 North Freeway. Adult male deceased at the hospital. 202329North officers are at a shooting scene 7600 North Freeway. Adult male deceased at the hospital. 202 https://t.co/9bGh6Kp6rFAccording to Casillas' sister Sandy Casillas, who made a statement following her brother’s death, witnesses in the area reportedly spotted the 29-year-old mechanic being chased by the customer around the auto-shop, moments before being shot to death.Luis Manuel Casillas was killed after an unidentified customer refused to pay the repair billImage via Screenshot/TwitterAs per ABC News, Luis Manuel Casillas was killed after he got into a heated argument with an unidentified customer who reportedly showed up at his auto shop with five men. According to witnesses, the customer reportedly refused to pay the bill, leading to a verbal altercation between Casillas and the assailant.Shortly after, Casillas was chased around the shop and shot despite the victim pleading for his life with the suspect. Sandy Casillas told the outlet:“My brother started running. He ran through all the side businesses he could run through. They did catch up to him, and they shot him in the head. (Point) blank. They put him on his knees, and they shot him in the head.”Sandy added that moments before her brother was shot to death, he implored for his life to be spared by the assailants, asking them to take whatever they wanted from the shop. In a statement to another outlet, KTVU, Sandy Casillas said:"They didn't just take $500. They took a life, they took our life, they took a father. You don't do that to any human beings," she told KTRK. "You don't do that to animals. How do you do that to my brother?"Police have yet to arrest the suspect in Luis Manuel Casillas' deathImage via screenshot/TwitterFollowing the incident, Luis Manuel Casillas' family gathered around the crime scene demanding justice for the victim. However, Houston police have yet to arrest the suspects responsible for the killing. In a press release, the Houston Police Department said:"Detectives are investigating the events leading up to the shooting and aiming to recover possible video footage of the incident.”Houston Police@houstonpoliceNortheast officers are at a shooting scene 4100 Bennington. Adult male deceased at the scene. 2022712Northeast officers are at a shooting scene 4100 Bennington. Adult male deceased at the scene. 202 https://t.co/UI7dOqhOoqMeanwhile, the victim's family told the outlet that they had shared the information of an individual, who they believe to be a potential suspect, with the authorities.