TUCSON, Ariz. (Reuters) - An Arizona jury on Tuesday said it was unable to reach a verdict in the trial of a U.S. human rights activist who was accused of hiding undocumented migrants, but said he was offering them humanitarian aid.

The Tucson jury remained deadlocked after three days deliberating charges against Scott Warren, 36, stemming from his January 2018 arrest by U.S. Border Patrol in Ajo, Arizona.

The split among the jurors reflected divisions in public opinion on how the United States should treat illegal border crossers after U.S. President Donald Trump made border security a signature issue.

Federal prosecutors argued that Warren was part of a conspiracy to illegally transport and conceal the two men at a ramshackle building used by activists who provide water, food and first aid to migrants.

Lawyers for the geography professor said he was exercising his legal right to provide aid to people crossing Arizona’s southern deserts, where over 3,000 migrants have been found dead since 2001, and thousands more have disappeared.

“In the time since I was arrested in January 2018, no fewer than 88 bodies were recovered from the Arizona desert,” Warren told reporters after U.S. District Court Judge Raner Collins declared a mistrial. “The government’s plan in the midst of this humanitarian crisis? Policies to target undocumented people, refugees and their families.”

Federal prosecutors now have the option to request a new trial, with a new jury, at a hearing set for July 2. They could also drop charges against Warren, who faced nearly 20 years imprisonment if convicted on all counts.

The trial sometimes veered into U.S. immigration policy, with jurors read an opinion piece by Warren in which he warned that his conviction could set a precedent allowing the Trump administration to expand prosecutions for harboring migrants.

“The government has failed in its attempt to apply federal charges to acts of common compassion,” tweeted No More Deaths, the aid group Warren volunteers for.

Federal prosecutors said Warren’s talk of deaths and suffering were a “smokescreen” for his attempt to smuggle migrants.

Warren testified in his own defense, telling jurors his spiritual values compelled him to help those who “stumble” out of the desert into Ajo.

Over 137,000 people signed a petition demanding he be released and United Nations officials called for charges to be dropped, arguing that “providing humanitarian aid is not a crime.”