HOUSTON, Texas -- The man charged with shooting three Houston police officers used guns with homemade parts, and he was already on police radar before Thursday's shootout, according to ABC13 sources and court documents.
Roland Caballero, 31, has been charged with three counts of attempted capital murder. He is accused of shooting three Houston police officers earlier this week.
Officers N. Gadson and D. Hayden are recovering at home. As of Friday night, Officer A. Alvarez remained hospitalized and is stable, according to HPD.
Caballero is also still in the hospital, but under arrest. He has a gunshot wound to the back of his neck.
According to court records, Caballero was already under investigation. A witness told police prior to the shootout that he was producing gun components called "switches" that turn semi-automatic pistols into fully automatic ones, court records say, and when SWAT officers heard his name over police radios, they knew exactly where to go to find him. In fact, they had been there before.
RELATED: 13 Investigates explosion in illegal 'Glock switches'
After an hours-long standoff, Caballero surrendered with his hands up.
Houston police recovered one gun, which had been modified to produce rapid fire, from the car that he was driving. They recovered a second gun he was carrying as he ran away from another scene. A neighbor's cell phone captured it on camera. Police believe both potentially had parts that were created on a 3D printer.
"They call it a 'ghost gun.' The untraceable gun, because it doesn't have a serial number. It was made at home," explained James Hillin, the owner of Full Armor Firearms and Gun Range on the Katy Freeway.
Hillin sells and manufactures guns legally. He also has 3D printers but alleged criminals want them for different reasons.
"If he can 3D print this stuff, he can sell it and he can sell it to a lot of people for a lot of money because of the allure of the 'ghost gun,'" said Hillin.
According to court records, Caballero was already being investigated.
Friday morning, Houston firefighters sawed open a safe so that investigators could collect what was inside.
Caballero could face more charges. When he is well enough, he will be transferred to the Harris County jail and will face a judge.
Police pull evidence from Fifth Ward home after standoff with man accused of shooting 3 HPD officers
ABC13 exclusive video shows chase suspect crash near downtown and injure 3 officers in shootout
WATCH: Surveillance video shows the moment gunfire was exchanged between officers and suspect
WATCH: Video shows suspect carjack woman after firing at officers