A Texas father is accused of shooting dead his 22-year-old son for coming to the defense of his mother during a heated domestic argument. Harris County Sheriff's officials say Ulysses Beaudoin, 39, gunned down Ulysses Nelson Tuesday night after showing up at the family's home in Katy with his mistress in tow. Deputies say the deadly confrontation took place at around 9amm at 6622 Gordon Drive in the Bear Creek Meadows subdivision. Scroll down for video . Filicide: Ulysses Beaudoin (left), 39, of Texas, is accusing of killing his 22-year-old son and namesake, Ulysses Nelson (right), when the young man tried to intercede on behalf of his mother during a domestic argument . Crime scene: The deadly incident took place inside the family's home in Katy, texas, Tuesday night when Ulysses Beaudoin arrived with his girlfriend in tow . Beaudoin had pulled up to the house in his Ford SUV and went inside. His girlfriend, who has not been named, remained in her own car around the corner. Moments later, Beaudoin got into a fight with his wife of 18 years, Christina Nelson, in the master bedroom, reported Click2Houston. When the couple's 22-year-old son tried to intervene, deputies say the father pulled out a 9mm handgun and shot him twice in the back. The armed man then allegedly threatened his 18-year-old son, sending the teen fleeing for his life. The boy ran to a neighbor for help, crying hysterically and begging her to call 911 and then check up on his older brother, who had been shot. Nelson was pronounced dead at the scene from his wounds. Protector: Deputies say Beaudoin and his wife of 18 years, Christina Nelson (right), got into an argument in the bedroom, prompting their son (left) to step in . In cold blood: Beaudion allegedly pulled a 99m handgun on his 22-year-old son and shot him twice in the back . Pursuit: The 39-year-old suspect jumped into his girlfriend's car and fled, but police tracked him down at a nearby Shell gas station . Crocodile tears: The 39-year-old suspect was seen weeping and muttering, 'My baby,' as he was being handcuffed . An infant was also present in the house at the time of the shooting but escaped unharmed, according to ABC13. According to investigators, the gunman then jumped in his girlfriend’s Dodge Charger and the two fled the scene, but responding officers tracked them down and arrested Beaudoin at a Shell station near the house. The 39-year-old suspect was seen weeping as he was being handcuffed, reported the news site Covering Katy. At one point, he cried out, 'My baby,' presumably referring to his dead son. Ulysses Beaudoin is now facing a murder charge in Nelson’s slaying.
Ulysses Beaudoin, 39, of Texas, allegedly shot his son, Ulysses Nelson, twice in the back .
Officials say he then threatened his 18-year-old son with 9mm handgun .
Beaudoin and his girlfriend fled from the scene but were tracked down .
The father was seen weeping and muttering, My baby,' as he was being handcuffed .