They say Aaron Leach-Veliz, 42, was hiding in the bushes when his wife, Armandina Leach, 44, drove up to their home with their 16-year-old son.
Police say Leach-Veliz shot Leach several times while their teenage son watched.
She later died at Ben Taub Hospital, but Leach-Veliz ran away. He hasn't been seen since.
"My wife even asked me if we should check our backyard," said one neighbor, "because we won't know what's going on."
The couple separated last week, after several years of marriage. Their two children, 16 and 11, are staying with relatives.
"Tell him to come forward. Whatever he does right now, he already did," said family friend, Maria Elena Pana. "He's not going to bring her back. He already took the mom of their children. "