After a young girl was abducted on the Navajo Nation and found dead near a towering rock formation, tribal officials faced tough questions about why an Amber Alert system proposed years earlier was never implemented.

Now, Navajo officials' proposals to build one of their own to cover the 27,000 square-mile reservation, which would be the first specifically for tribal land, is drawing attention to the systems they've been using with Arizona, New Mexico and Utah.

The states' systems that encompass the Navajo Nation are similar but different enough, officials say, that they can keep alerts on child abductions from being sent out simultaneously and broadly, most notably in civil child custody cases.

In those, Arizona and Utah require an indication that the child is at risk of serious injury or death but not for New Mexico.

Navajo officials said they followed protocol in getting the word out on the May 2 disappearance of 11-year-old Ashlynne Mike but also that they failed her in not having an alert issued until early the next day in New Mexico. It was broadcast briefly in Arizona.

"Those are the challenges on how we're going to bridge those gaps and get those alerts out," said Harlan Cleveland, who recently was named Navajo Nation's Amber Alert coordinator. "We still have to call each state and say, 'here's what's going on.'"

Cleveland's counterparts in New Mexico, Arizona and Utah say they're supportive of the tribe's efforts to create an independent alert system, saying better communication is needed between state and tribal officials.

But not all believed it was necessary, given the extensive reach of alerts through television and radio broadcasts, cellphones, roadside electronic billboards and, in Arizona, the state lottery. "It's that adage of why reinvent the wheel," said Chrystal Moore, Arizona's coordinator. "It's working."

The Navajo Nation is approaching a self-imposed 60-day deadline to have a system in place, set shortly after a stranger lured Ashlynne into a van, and sexually assaulted and bludgeoned her.

Cleveland said the ultimate goal is to alert anyone on the reservation about natural disasters, weather emergencies, and missing and endangered people but that will take time. For now, the tribe is partnering with the states, getting hundreds of tribal first emergency responders trained on Amber Alert and ensuring everyone knows who to call when a child is missing.

About one-fifth of the 567 federally recognized tribes have plans that outline criteria to request the alerts, said Jim Walters, program administrator for Amber Alert training at Fox Valley Technical College in Wisconsin. No tribe directly activates the alerts, instead relying on state or regional systems, he said.

According to the National Center for Missing and Exploited Children, few American Indian children are subject of Amber Alerts each year. In 2014, the center counted eight, or 3 percent. It doesn't distinguish between child abductions on or off tribal land.

Earlier this year, the Fort Peck Assiniboine and Sioux Tribes of Montana had two Amber Alerts issued for missing children.

In one case, a woman who was caring for a 13-month old female relative reported that the girl went missing, triggering an Amber Alert that was broadcast in Montana and North Dakota. Authorities canceled it after the woman confessed to killing her and drew a map that led them to the baby's body.

The Navajo Nation was tested about a month after Ashlynne's death when two boys from Wheatfields, Arizona, went missing. The Amber Alert issued for the boys was the first in which the tribe directly requested it from a state agency. The boys were found safe.

In 2007, the tribe participated in a U.S. Department of Justice pilot project to expand Amber Alert awareness into Indian County. The tribe elected to create a regional system, named an Amber Alert coordinator, wrote a policy and was awarded $330,000 in federal funding.

About half the money went to megaphones, portable electric heaters, pop-up tents and other equipment but the rest intended for public education went unspent. The program crumbled after the tribe's acting chief of criminal investigations at the time left the job.

Staff turnover, scant resources, poor communication networks, cultural taboos about speaking of traumatic events, non-existent cellphone signals and remote areas where a police response can take hours can be challenging for tribes, law enforcement experts say.

The Amber Alert system is set up to work best within the first five hours a child goes missing. If a child isn't found within three hours, the chance of being found alive decreases by 75 percent, said Art Brooks, director of the Arizona Broadcasters Association, which helps implement the state system.

Robert Platero, the tribe's former Amber Alert coordinator and a member of the task force, said tribal communities need to be educated on missing and endangered children and be able to count on police to spread the word quickly but carefully.

"We need to maintain the integrity of the system," he said. "We can't just be screaming wolf."