Yolo County will not file criminal charges against UC Davis police officers who pepper-sprayed student demonstrators last November, the Yolo County District Attorney's Office said Wednesday, ending its probe into the officers' response to campus protesters.

In viewing the incident "through the totality of the circumstances, there is insufficient evidence to establish proof beyond a reasonable doubt that the use of force involved in the November 18, 2011, pepper spraying was unlawful and therefore warrants the filing of criminal charges," officials said in a statement announcing the report's findings.

The response by campus police clad in riot gear – punctuated by the image of police Lt. John Pike calmly pepper-spraying seated student protesters – was met last fall with international scorn.

Withering reports from a specially convened task force led by former state Supreme Court Justice Cruz Reynoso, and Kroll, an independent consulting firm, described a dysfunctional police force and the "systematic and repeated failures" of university leaders to manage the incident.

Pike was later relieved of duty; his police chief, Annette Spicuzza, retired; UC Davis Chancellor Linda P.B. Katehi withstood calls to resign, but was later censured by the UC Davis Academic Senate for failing "to perform adequately the tasks of her office."

Officials with the Yolo County District Attorney's Office said their document relied heavily on the Kroll report, which acknowledged that Pike and the officers believed they were "surrounded by a hostile 'mob' and that the pepper spraying was necessary to clear the pathway so that the officers and their prisoners could leave the Quad safely."

UC Davis' internal affairs report on the incident, a copy of which was obtained by The Bee this summer, concluded that Pike acted reasonably during the protest.

A subsequent review determined that Pike should have faced demotion or a suspension at worst, according to documents obtained by The Bee.

The internal report found that Pike had repeatedly warned students who had gathered on the quad to protest rising tuition costs that they would be pepper-sprayed if they did not disperse, and that "the police officers were fully encircled by protesters who had locked arms and would not let the officers exit."

When contacted Wednesday, Pike said he had not heard of the decision by the district attorney, but added that he was "extremely relieved."

"I have not reviewed or seen their report, but I am relieved at knowing they are not going to be bringing any charges," Pike said.

UC Davis officials had no official comment on the report Wednesday, saying the district attorney's report stood on its own.

But Alexis Briggs, San Francisco-based attorney for the Davis Dozen, the Occupy-style protesters who face charges in Yolo Superior Court related to demonstrations at a campus U.S. Bank branch in February and March, and whose clients include students who said they were pepper-sprayed, was dismayed by the report's findings.

"I guess the Reynoso report, the Kroll report and video is sufficient in some cases but not in others. I'm sorry to hear that," Briggs said.

"There seems to be a willingness to rely on video evidence in some cases but not others. My thoughts go back to the day itself," she said, adding the events "cast doubt that Lt. Pike and others were acting lawfully."

Kroll investigators determined campus police had not been trained or authorized to use the pepper spray fired at demonstrators.

University of California regents last week approved a settlement providing compensation to 21 students and former students struck with pepper spray in the November incident.

The incident has cost UC Davis more than $1 million in legal and other fees.

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