A single border sector in Arizona prosecuted 565 people who were arrested for making a first attempt to illegally cross into the U.S., the Customs and Border Protection announced Thursday.

Trespassing into the U.S. is a misdemeanor the first time and a felony every time thereafter, though most apprehended trespassers are not charged for the first offense.

The Tucson Sector changed that policy and started prosecuting all illegal entrants June 1, citing the act as a violation of the United States Code.

"The purpose of this measure is to dissuade migrants from risking their lives to cross illegally through the inhospitable Sonoran Desert. By adding criminal consequences to all apprehensions, Tucson Sector plans to make the west desert region even more undesirable place to cross," CBP said in a press release.

Tucson Border Patrol agents rescued 80 people in the west desert who had attempted to illegally enter the country in June alone.

"Arizona's desert shows no mercy for those unprepared for its remote, harsh terrain and unpredictable weather," the agency added.