Transcript for Gunman caught on camera killing woman at garage sale

Now to the urgent manhunt for a gunman who is seen approaching and killing a woman in Texas while she set up for a garage sale. Police are pleading for the public'selp and ABC's Marcus Moore is there in Tomball, Texas. Reporter: The victim's family is desperate for answers this morning and so are investigators who have a critical clue. They have surveillance video showing what happened in this front yard and we have that video and we're not going to show you the actual shooting but the footage is still disturbing to watch. This morning, police looking for the person who was caught on tape fatally shooting a woman, Elizabeth Barraza while she was setting up a garage sale in her driveway. In this chilling surveillance video from January 25th, someone approaches Barraza in her Tomball, Texas, driveway at 6:55 in the morning. The two appear to talk briefly then seconds later Barraza is shot four times at point blank rank. We are not showing you the actual murder. The killer is seen then running away before getting into a dark vehicle and driving off. We need justice for Liz. I need justice for Liz. I love you, Liz. Reporter: Barraza's husband left for work that morning at 6:48 A.M. Police say the shooter's truck can be seen pulling up to the area four minutes later. The couple was supposed to leave for a trip celebrating their fifth wedding anniversary two days after she was shot. Police looking for any clues in this case shrouded in mystery. Investigators not certain if the suspect is male or female. Have made no arrests and have yet to determine if Barraza was targeted. Authorities say she only put up signs for the sale that morning. Our investigators were able to gather some critical surveillance from homes in the neighborhood of the vehicle. But as of today our investigators still need vital information to solve this horrible crime. Reporter: There is a $20,000 reward for information in this came and Barraza and her husband, they are huge "Star wars" fans and Peter Mayhew who plays chewbacca in the films is now involved in helping to raise money. Everyone just hoping for a break in the case. Guys. We're all hoping for that. Marcus, thank you.

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