A trial began Wednesday for a man accused with two others of attacking a pair of Navajo transients as they slept and beating them to death in New Mexico's largest city, a crime that appalled residents and led to the creation of a special task force.

Authorities say the three defendants were teenagers when they killed Allison Gorman, 44, and Kee Thompson, 46, in a vacant Albuquerque lot in July 2014.

The jury trial for Alex Rios, now 20, started with opening statements before a packed courtroom.

According to police, Rios and the other two suspects beat Gorman and Thompson beyond recognition with a cinder block, metal pole and their hands and feet. One of the defendants told investigators the attack lasted more than an hour, according to a criminal complaint.

The killings shocked many in Albuquerque and led Mayor Richard Berry to create a task force on Native American homelessness.

Rios faces multiple charges, including two first-degree murder counts, aggravated battery with a deadly weapon and contributing to the delinquency of a minor.

The youngest of the three suspects was 15 at the time of the attack. Now 16, he has pleaded guilty to second-degree murder and other charges in a plea agreement that calls for him to testify against the other defendants. The agreement caps his potential sentence at 20 years but offers the possibility of release when he turns 21.

A month after the killings, Berry and other Albuquerque officials traveled to the Navajo Nation capital of Window Rock, Arizona, to discuss the framework and goals of the task force.

Ben Shelly, then-president of the Navajo Nation, called the killings appalling. He and Berry said significant work needed to be done to tackle the problem of homelessness among Native Americans.