There were audible gasps and sobs from the audience as the verdict was read. Family members of both Pacheco and Montoya were crying.
Montoya, convicted of first-degree felony murder and second-degree felony obstruction of justice, could spend the rest of his life behind bars.
"It's been a really hard day. It's been a really hard three years. I'm just glad justice is finally served," said Christine Garcia, the victim's aunt.
She said the verdict has soothed some of the pain from the killing. "Forgiveness takes time, but I'm not as angry as I used to be. I feel bad for Josh's family."
The guilty verdict was a blow for the Montoya family and the defense attorney.
"The verdict was shocking. We hoped and prayed. We're all hurting now," said Maria Montoya, Joshua Montoya's aunt. "We really thought it would be the other way, but I guess they got justice. So now we just have to pray for peace."
"It was devastating, very surprising and extremely disappointing," said defense attorney Isaac McDougall.
According to prosecutors, Montoya walked out of his home, near 5700 South and 4600 West, intending to kill Pacheco on that day more than three years ago.
He had a gun in his pocket as he walked past his children, who had been dropped off by Pacheco and their mother, and picked a fight with the man, prosecutors said.
Pacheco, who was dating Ana Torres, the mother of Montoya's three children, was seated inside her car. Prosecutors said he was tired, didn't feel well, meant no harm.
"The defendant came out of the house, went around the car, picked an argument with Amos then took out a gun," prosecutor Chou Chou Collins said. "When you shoot someone at that close range, the intent is clear."
Pacheco suffered a gunshot wound to his chest. He died at the scene.
Montoya, who testified in his own defense Wednesday, claimed it was self-defense. He told jurors that Pacheco had threatened him with violence and had pulled out a gun. When Montoya saw it, he had to defend himself.
But prosecutors said the gun was in Montoya's possession the whole time.
They pointed to DNA evidence as proof Montoya's DNA was found all over the gun, while Pacheco's was not.
Several members of Montoya's family testified that he did not own a gun. No gun paraphernalia was discovered inside the home when it was searched by police.
Defense attorneys argued that Montoya was angry when he saw Pacheco because Pacheco had been making threats for months, saying he was going to shoot Montoya in front of family members, friends and mutual acquaintances.
When Montoya saw Pacheco pull out something metal, they said, his fears were confirmed. That's when both men lunged for the gun, defense attorneys said.
They offered photographs of scratch marks on Montoya's face, neck and chest as evidence of a scuffle. They cited a medical examiner's report that indicates the gun was fired at an indeterminable range which can indicate a struggle took place.
"That doesn't show an intent to kill," McDougall said. "That's an accident. You're allowed to protect yourself with an appropriate amount of force if you're in fear for your life. Josh was in fear for his life."
But it was not enough to convince the jury.
After fleeing the scene, Montoya stashed the gun at a friend's house more than four miles away. Prosecutors argued this was plenty of time to concoct a bogus self-defense story to tell authorities.
Montoya will be sentenced this summer by Judge Deno Himonas.