A Bexar County jury on Friday found a man not guilty of murder in the fatal shooting of his mother’s boyfriend.Jurors deliberated for 2.5 hours before finding Gaien Perez not guilty of killing Luis Rosales in August 2022.Rosales, 39, was found dead in the 100 block of La Manda Boulevard down the street from his girlfriend’s house.Perez, who was still at the scene at the time, was later arrested and charged with first-degree murder.During testimo…