After more than a year of legal wrangling, federal prosecutors in Tucson dropped criminal charges against four humanitarian aid volunteers.

The volunteers with Tucson-based No More Deaths faced misdemeanor charges connected to driving on the Cabeza Prieta National Wildlife Refuge, southwest of Tucson, in July 2017. They were searching for three people reported missing during an illegal border-crossing, according to records at U.S. District Court in Tucson.

Caitlin Deighan was accused of driving in a wilderness area. She and Zoe Anderson, Logan Hollarsmith and Rebecca Grossman-Reicheimer also faced charges of entering a wilderness area without a permit, according to a Dec. 6, 2017, court document.

After the charges were dropped Thursday, the volunteers were issued civil infractions carrying a $250 fine each, No More Deaths said in a news release.

The U.S. Attorney’s Office could not be reached for comment, but the court docket says “the Government indicates that an agreement has been reached to settle this matter via the defendants’ payment of a collateral forfeiture.”

Based on that agreement, a hearing will be held March 4, according to the docket. “At the Government’s request, that hearing will remain scheduled to allow a brief record to be made regarding the agreement.”

The decision to drop the charges came a month after four other No More Deaths volunteers were convicted of misdemeanor charges connected to leaving food and water in the wildlife refuge. Another volunteer is scheduled to go to trial in May on similar charges, as well as felony human-smuggling charges.

“Today might be a victory for No More Deaths, but people continue to die and disappear every day in the desert,” Hollarsmith said in the news release. “Our hearts remain with the families of the disappeared. As long as border policy funnels migrants into the most remote corridors of the desert, the need for a humanitarian response will continue.”

Attorneys for Deighan and her co-defendants had asked the court to dismiss the charges because the volunteers were acting out of necessity in a life-or-death situation.

A woman in Phoenix called a No More Deaths hotline and said two of her cousins and a friend were lost near Growler Valley, an area of the wildlife refuge where many remains of illegal border crossers have been found, according to court records.

The volunteers called the Border Patrol, but agents didn’t respond for hours, their attorneys said. The volunteers went to the wildlife refuge to find the border-crossers, and the Border Patrol later sent a helicopter. One of the lost men was never found.

Last month, Natalie Hoffman was convicted of operating a motor vehicle in a wilderness area. Hoffman and Oona Holcomb, Madeline Huse and Zaachila Orozco McCormick were convicted of entering a national wildlife refuge without a permit and abandoning property there.

They are scheduled to be sentenced March 1.

Another volunteer, Scott Warren, faces similar charges for aid efforts on the wildlife refuge in June 2017. He also faces a felony human-smuggling charge after Border Patrol agents said he was harboring two illegal border crossers at an aid station in Ajo in January 2018.

Warren’s trial on the misdemeanor charges of driving in a wilderness area and abandoning property is scheduled to start May 6.

Contact reporter Curt Prendergast at cprendergast@tucson.com or 573-4224 or on Twitter:

@CurtTucsonStar