AJO, Ariz. (AP) -- An organization that helps migrants along the U.S.-Mexico border says volunteers found five separate sets of skeletal remains deep in the Arizona desert within five days.
The No More Deaths group said last week that the bodies were found from Dec. 16 through Dec. 20 in remote areas near Ajo, Arizona, by volunteers with the organization in Tucson and Phoenix, along with a group from Ajo.
The findings highlight the ongoing plight of migrants who travel through the rugged Arizona desert with its wildly varying temperatures. The Sonoran desert is extremely rugged and has daytime temperatures that can soar above 100 degrees in the summer and drop to below freezing overnight in the winter.
"It's really sad and it's really frustrating. They're deaths that are often ignored because it's a population of people who are coming from very poor areas and they face a lot of discrimination from obviously officials and the public as well," said Genevieve Schroeder, a spokeswoman for No More Deaths.
About 144 bodies of migrants were found in the Arizona desert in 2016, according to data gathered by the Pima County Office of the Medical Examiner, and Humane Borders, Inc., an advocacy group. That figure does not include remains found in December.
The Border Patrol reported finding 68 bodies in Arizona in the 2015 fiscal year that ended Oct. 1 of that year, although advocates claim that was a serious undercount. The federal agency reported 240 deaths in the entire country that same year.
During the first 11 months of the 2016 budget year that ended Sept. 30, 70 deaths were reported in the Border Patrol's Tucson sector, which covers most of the state. The Border Patrol says its counts only includes bodies found by agents on patrol, and excludes remains found by volunteers or local law enforcement agencies.
Deaths are significantly down in the Arizona desert since a surge of border crossings by migrants in the mid-2000s. According to the medical examiner's 2015 annual report, remains recoveries peaked at 223 in 2010 and averaged 171 per year between 2002-2015.
But advocates say that's only because migrants are coming through different areas and risking their lives in places like Texas, which has seen a large increase in border crossers.
"It's tragic and it's really infuriating because these are deaths that are completely unnecessary and they're deaths that are caused by U.S. border policy," Schroeder said.
Schroeder said the Border Patrol intentionally funnels migrants into remote areas where their likelihood of survival is low.
The Border Patrol in a statement did not directly address that claim but blamed many deaths on smugglers who "knowingly victimize people wanting quick passage into the United States.
"Smugglers lie, telling their 'customers' their passage will be safe, but in reality, the terrain is treacherous and the conditions are extreme," the statement said. "Many are led to their deaths by smugglers more concerned about making money than they are about the lives of others."
The Border Patrol also said it deploys resources to areas with the majority of deaths and has 36 rescue beacons placed across the region's mountains and deserts.
"We collaborate closely with foreign government officials, law enforcement partners, and community organizations to educate potential migrants about the true dangers of crossing the border illegally," the statement added.
In past years migrants who came through Arizona were found closer to the central part of the desert. Now many are going through the more rugged area to the west near Ajo, Schroeder said.
Most of the remains recovered in 2015 were men. The vast majority of those whose cause of death could be determined died of exposure.
Schroeder said No More Deaths formed a coalition with a group called Ajo Samaritans who go out daily in the remote desert to search for migrants.
Volunteering requires skill in hiking and organizations look for people with medical experience and who can speak Spanish. This month volunteers have gone out in groups of three to five on a daily basis, although that might slow down in the coming year, Schroeder said.
When volunteers find bodies, they call local authorities and work to ensure they investigate.
Identifying long-decayed remains of migrants is challenging because there are typically no U.S. records that could help identify them, such as dental X-rays or DNA samples.
The Pima County's medical examiner works with local nonprofits to help identify remains.
The Border Patrol said it has partnered with local foreign consulates, the Pima and Maricopa county medical examiners and other law enforcement agencies as part of the Missing Migrant Program to try to rescue missing migrants or recover and identify the dead.