By Eric M. Johnson

SEATTLE (Reuters) - Federal prosecutors said on Tuesday they lack sufficient evidence to file criminal charges against three patrolmen in Washington state for the fatal shooting of an unarmed Mexican orchard worker who threw rocks at them and ran.

The killing of Antonio Zambrano-Montes in the southeastern farming hub of Pasco in February 2015, captured on video and shared widely online, sparked days of protests from the city's majority Latino community and drew criticism from the Mexican government and human rights activists.

Zambrano's death was among a series of police shootings across the United States that have put law enforcement agencies under scrutiny over their use of force against minorities.

Michael Ormsby, the U.S. Attorney for the Eastern District of Washington, said prosecutors determined that police did not violate Zambrano's rights under a federal criminal civil rights statute.

"There is insufficient evidence to prove beyond a reasonable doubt that they acted willfully, that is, with a bad purpose to violate the law," Ormsby wrote to Zambrano's family members in a letter reviewed by Reuters.

The decision came nine months after a county prosecutor declined to file criminal charges against officers Ryan Flanagan, Adam Wright and Adrian Alaniz.

Flanagan, who resigned from the police force after the incident, and Wright and Alaniz, who were placed on paid leave following the incident, were cleared of wrongdoing and allowed to return to duty.

Scott Johnson, an attorney for Flanagan, said in a phone interview he was not surprised by Ormsby's decision. "Every law enforcement agency that has reviewed the case has come to the same conclusion: there was no criminal activity on the part of the officers."

The officers fired 17 shots at Zambrano after he ignored orders to stop throwing rocks near a crowded intersection, police said. Zambrano jogged across the street as the officers chased him, and he collapsed seconds later on a sidewalk after a volley of gunfire.

"When he then turned to surrender, they shot him to death," his mother, Agapita Montes Rivera, said in a statement provided by her attorney Charles Herrmann. "Where is justice for my son?"

Zambrano's family filed a civil wrongful-death lawsuit in federal court in 2016 accusing the officers of excessive force. A trial has been set for May 2017.

Zambrano, an undocumented immigrant who arrived in Washington state's apple-growing belt seeking opportunity about a decade ago, battled drug use and homelessness leading up to the shooting.

(Reporting by Eric M. Johnson in Seattle; Editing by Richard Chang)