HPD released new details Monday that may explain the motive.
Brianna Navarro, 22, was a passenger in her boyfriend’s car when someone in a dark-colored coupe opened fire on the vehicle.
One bullet hit Navarro in the back and she died at the scene.
"I said, 'Oh, Lord, please don’t take her,'" Navarro's grandmother Maretta Ramon said. "But she was already gone by the time they told me."
On Monday, investigators said the boyfriend had an altercation with someone at a nearby convenience store before the shooting. He said the man followed them and opened fire on the car around 1:10 p.m. in the 11200 block of Richmond Avenue.
Navarro's 2-year-old son was also in the car at the time of the shooting but wasn’t physically hurt. Neither was her boyfriend.
Relatives say Navarro was about six months pregnant and also had a 6-year-old son.
"She was totally excited. She was buying all kinds of stuff for him she was going to have another little boy," Ramon said.
Ramon said she doesn't understand why anyone would take the life of such a kind young woman and has a message for the killer.
"She would give you the shirt off her back no matter what," Ramon said. "Turn yourself in. Do the right thing. Turn yourself in. We can forgive you because we are forgiving persons."
Police said they're looking at surveillance video to help identify the gunman.
Anyone with information in this case is urged to contact the HPD Homicide Division at 713-308-3600 or Crime Stoppers at 713-222-TIPS.
A GoFundMe campaign has been started to help the victim's family pay for funeral expenses. As of Monday, it has raised more than $5,100 toward its $10,000 goal. Click here to donate.