Arnez Markel Semien, 19, and Jonathan Lopez, 17, were arrested on Thursday and charged with capital murder, according to Houston police.
They join Daniel Medrano, 20, and Andres Lara, 19 -- who were both arrested on the same charges earlier this month.
READ MORE: 2 suspects charged with capital murder in death of man attempting to thwart robbers in Spring Branch
2 suspects charged with capital murder in death of man attempting to thwart robbers in Spring Branch
On March 28, police found 43-year-old Joel Villarreal unresponsive with a gunshot wound outside Lighthouse Smoke and Vape shop at 7550 Long Point Road.
Villarreal was taken to the hospital, where he was pronounced dead.
ORIGINAL REPORT: Man shot and killed in Spring Branch was trying to stop smoke shop robbers, HPD says
Man killed while possibly trying to stop smoke shop robbers
A preliminary investigation determined that an armed robbery had just occurred. Villarreal was trying to stop the suspects from fleeing, sparking a shootout between them, police said.
"A bystander tried to intervene. They got into a shootout," Det. Chettry with HPD said. "The bystander was wounded and transported to the hospital, where he succumbed to his injuries."
Further investigation revealed a person of interest wanted for questioning. HPD released a photo of Lara on April 3.
RELATED: Man sought by police after 43-year-old shot and killed while trying to stop robbers in Spring Branch
Three days later, a subsequent investigation identified Lara and Medrano as the suspects, and they were both arrested and charged for their roles on April 6.
Then, even further investigation also identified Semien and Lopez as suspects. They were arrested and charged on April 27.
It was discovered that one of the suspects, Medrano, was already out on bond for a capital murder charge stemming from 2022.
In a previous report, Medrano was one of three suspects accused of fatally shooting another man, identified as 20-year-old Jordan Capuchino, in the 6600 block of Maybank Drive after an armed robbery at a nightclub on September 17, 2022.
SEE ALSO: Family desperate for answers after loved one killed while trying to stop robbery on Long Point Road
Family searches for answers after man trying to stop robbery killed