EL PASO, Texas (Border Report) – A new search for more than a dozen migrants missing for several weeks in the desert of northern Chihuahua came up empty, but Mexican officials say they found evidence of human smuggling in the area.

The Sunday morning search involved a Mexican army UH-60 Black Hawk helicopter and several 4-by-4 land vehicles canvassing a 100-mile-wide area between Juarez and Ojinaga. The search party was following up on tips to the whereabouts of 13 missing Mexicans headed for Odessa, Texas, who were allegedly abducted along with their guide west of Ojinaga in late September.

Another migrant, a Mexican with learning disabilities named Omar Reyes Lopez who got separated from his group, also has been missing in the area since November.

Authorities focused on towns in Juarez’s East Valley like Guadalupe and Praxedis, and eastward toward ranches near the U.S. border such as Cieneguilla, Bosque Bonito and Lomas de Arena, according to the Chihuahua state police, which participated in the search.

No persons were found but the land units came across abandoned vehicles and makeshift camps they believe have been used by migrant smugglers.

“We recognize the efforts of the government of Chihuahua […] however, the problems on this part of the border exceed their capabilities,” said Sheila Arias, a relative and human rights activist who has been spearheading the search for Reyes.

She said more than 30 migrants headed to the United States in that stretch of border have gone missing in the past 18 months.

“It’s evident that organized criminal groups control the area, and that endangers our migrants,” Arias said. “We cannot ignore this reality, not the families of the missing nor society at large nor the authorities.”

U.S. Border Patrol officials, members of Congress who represent border states and binational security experts have talked to Border Report at length about the growing involvement of Mexico’s drug cartels in migrant trafficking, which they consider a high-reward, low-risk business.