Lawrence Ballesteros was stabbed to death in Sept. 2012, just days after a sex offender sweep.
An autopsy showed Ballesteros was stabbed 58 times before his body was dumped near Chandler Airport.
Investigators believe the attack stems from the kind of anger you'd expect from a parent who just found out a pedophile had become a family friend.
When U.S. Marshals and local police went door-to-door tracking sex offenders, Lawrence Ballesteros was right where they expected him. The sting apparently blew his cover, though, and made him a target.
"There was a big uproar in this neighborhood," said defense attorney Gerald Schwab. "There were a lot of angry people confronting him about this report of him being a sex offender."
Less than a week later, a group of early morning walkers found him dead on a frontage road a mile from the detached garage where he was living.
Police arrested David Barrera and Patricia Perez for murder. Perez lived in the front house with her partner and their children. Investigators say she and Ballesteros were drinking buddies, and Barrera often joined them. They believe the shock of the revelation drove Barrera and Perez to kill their friend.
"That's exactly what they're saying is this is a case of vigilante justice -- my client killing somebody because he was a sex offender - however, there's no evidence to prove that," said Schwab, who represents Barrera. "There's no murder weapon. There are no eyewitnesses."
There is a Barrera fingerprint in Ballesteros' apartment, though. There's also video of his truck in the area where Ballesteros' body was dumped. Investigators found the victim's blood in that truck. But with no confession, prosecutors may have to dig deeper.
ABC30 legal analyst Tony Capozzi says a history of abuse could connect the suspects to this murder because of the brutality of the attack.
"Clearly it's a crime of emotion," he said. "It appears there's some anger and deep-seated hatred was involved here."
The judge in the case has ruled she won't allow evidence of Barrera's or Perez's personal history of abuse or crime unless they testify in the case. Defense attorneys say they're not likely to open that door.
Opening statements in the trial are expected early next week.