SAN JOSE — The Santa Clara County District Attorney’s Office said Thursday that no criminal charges are warranted against a San Jose police officer whose combative anti-protest tweets drew wide scorn amid a heated national conversation over police-community relationships.

While cleared of criminal conduct, the police career of Officer Phillip White, a 20-year SJPD veteran, remains in jeopardy. He has been on paid administrative leave since a series of his tweets surfaced on the Buzzfeed website in mid-December.

The most inflammatory tweets read, “Threaten me or my family and I will use my God given and law appointed right and duty to kill you. #CopsLivesMatter” and “By the way if anyone feels they can’t breathe or their lives matter I’ll be at the movies tonight, off duty, carrying my gun.”

But the DA’s office determined the social-media posts did not constitute criminal threats or any other crime for which they could file charges, primarily because prosecutors could not pinpoint anyone who felt specifically threatened, including those who engaged with White on Twitter.

“The officer’s tweets were inappropriate and unprofessional,” District Attorney Jeff Rosen said in a statement. “Communicating something disturbing is not a crime, unless it is an intentional and specifically-aimed threat. Civil communication between the police and members of the public is important in establishing and maintaining trust.”

White could not be immediately reached for comment.

Legal experts told this newspaper in December that free-speech protections would likely shield White from any criminal penalties, but would not preclude him from discipline or termination if police commanders decided his effectiveness as a police officer was diminished, particularly in earning community trust.

Both police brass and the police union denounced the comments, which spurred an online petition as well as a local march led by area social-justice groups calling for White’s firing. An internal investigation continues into the tweets as well as White’s future with SJPD.

Prosecutors on Thursday also revealed new details about what White may have been responding to when he posted the infamous tweets. The officer made earlier posts criticizing protesters that drew angry responses on his Twitter feed, many of which came while White was out of town working as an assistant basketball coach for Menlo College, said Luis Ramos, the supervising district attorney who reviewed White’s case.

That included a message urging him to call his campus line, where White found a voice mail saying, “Hey you little (expletive), you should really be careful who you talk (expletive) on Twitter, punk. Don’t think I won’t (expletive) show up either,” implying he knew where the officer lived, Ramos said.

Menlo Park police investigated that call, but Ramos said an officer there “seemed to think it was going nowhere.”

Amid the controversy, Menlo College cut ties with White, issuing a statement saying the school “will not be represented by expressions of intolerance and bigotry on the campus, on social media, or on the Internet.”

While his case is examined, White cannot carry a concealed firearm, since a routine condition of administrative leave is that he must surrender the badge and police ID that allowed him to carry a weapon off duty without needing a concealed-carry permit from the county.

Demonstrators have been protesting what they view as widespread racial injustice by law enforcement, in the wake of grand juries declining to indict white officers in the deaths of African-Americans Michael Brown in Ferguson, Missouri, and Eric Garner in Staten Island, New York. Garner’s last words — “I can’t breathe” — have become a rallying cry, and #BlackLivesMatter now is a common social-media hashtag.

Police across the country have pushed back, criticizing fringe movements that have advocated violence against officers. In the Bay Area, the police unions in San Jose, San Francisco and Oakland — where anti-police demonstrations were a nightly fixture for much of December — issued a joint statement last month calling for constructive dialogue rather than the vilification of police.

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.