A Texas man is asking witnesses to come forward after his brother was shot and killed last week along a Houston highway, in what investigators believe was a road rage-motivated attack.

Alex Amaya, 46, was found dead in his car, on the side of the Sam Houston Parkway on June 3. Amaya was reportedly home from work at a drilling tool company, when he was shot in the head. The Houston Police Department is investigating the killing but has yet to determine a motive or find any suspects.

"[He was shot] on a busy freeway in broad daylight. There were cars in every lane," the victim's brother, Dan Amaya told KHOU.  "I mean, how could someone not see something?"

Amaya's death has "devastated" his family members - who were already struggling with another tragedy.

"Alexander's mother, Martha Amaya, has faced immense hardships since losing her husband to COVID-19 in October 2020," a family friend wrote in a GoFundMe post. 

"Now, she is grappling with the unimaginable pain of losing her son. Alexander leaves behind his mother, two brothers, Dan and Jason Amaya and his nephews and nieces whom he loved with all his heart."

Dan described the pain of losing his brother as being like "a sledgehammer" hitting him through the heart.

"The message that I have," Dan told KHOU "for the person who did it [is]: Find it in your heart and do the right thing, turn yourself in."