Man Is Arrested in Death of Jewish Protester Paul Kessler After California Altercation

It was, at first, the usual kind of interaction that takes place at dueling rallies. An argument between two opposing protesters, each firm in his beliefs.

But the encounter this month in a suburb just northwest of Los Angeles would end in tragedy, with one of the men on the concrete, suffering a head injury that would turn fatal.

The victim was Jewish. The other man, a pro-Palestinian demonstrator.

From there, the altercation was swept onto the global stage, with contentious opinions about who was to blame for what. As the local sheriff’s department investigated, outrage grew over the fact that no arrests had been made.

On Thursday, the authorities arrived at the home of Loay Alnaji, 50, a community college professor who lives in Moorpark, Calif., and arrested him, with bail to be set at $1 million.

The Ventura County district attorney, Erik Nasarenko, announced hours later that he would charge Mr. Alnaji with two felonies: involuntary manslaughter and battery causing serious injury. Prosecutors also accuse him of personally inflicting great bodily injury, which could increase the sentencing time if he is convicted.

For some, it was the first sign of justice in the 10 days since the victim, Paul Kessler, 69, died at the hospital. Mr. Kessler’s death, while thrusting the local community into the headlines, also became a flashpoint for the Israel-Hamas war, a deadly example of rising tensions even from thousands of miles away.

The Ventura County medical examiner, Dr. Christopher Young, determined that Mr. Kessler had died from blunt force trauma to the back of his head and ruled his death a homicide, which meant that another person had been involved. But Dr. Young also made it clear last week that his was a clinical determination, not a criminal one.

The incident from the beginning was clouded by conflicting statements from witnesses. And the authorities said that surveillance footage and other video from the scene offered impeded views of the encounter, adding that it was not “exactly crystal clear” how Mr. Kessler had died.

Jim Fryhoff, the Ventura County sheriff, asked for calm last week as his office investigated whether Mr. Kessler’s death should be criminally charged as a homicide and hate crime. He said the pro-Palestinian demonstrator involved in the altercation had made one of the 911 calls and remained at the scene.

The announcement of the arrest on Thursday included a call for community members with information to come forward, particularly anyone who had been driving that day in a vehicle with video-recording equipment. Sheriff Fryhoff is scheduled to speak at a news conference on Friday along with Mr. Nasarenko.

News of the arrest quickly spread within the local Jewish and Muslim communities.

“This arrest shows that violence toward our Jewish community will not be tolerated,” the Jewish Federation of Greater Los Angeles said in a statement. “We will continue to monitor the case to help ensure justice is served. Our heartfelt condolences continue to be with the family of Paul Kessler, and may his memory forever be a blessing.”

The competing rallies took place on Nov. 5 in Thousand Oaks, an affluent bedroom community, at a main intersection with heavy traffic that has served as the backdrop for past protests. About 100 people had arrived and Mr. Kessler was standing on the same corner as a Shell gas station, holding an Israeli flag.

Witnesses said Mr. Kessler had gotten into an argument with a pro-Palestinian demonstrator and fell during the altercation, sustaining a head injury, according to the sheriff. Mr. Kessler was conscious and responsive when law enforcement officers arrived at the scene, and at the hospital when they spoke to him again, the sheriff said. But he died hours later, in the early morning hours of Nov. 6.

The Jewish Federation said in its initial statement last week that Mr. Kessler had died after being “struck in the head by a megaphone wielded by a pro-Palestinian protester,” an explanation that circulated quickly among members of the Jewish community. Jonathan Oswaks, a witness who was supporting Israel at the protest, said in an interview that he saw the pro-Palestinian protester swing a megaphone at Mr. Kessler but was not sure if he had been struck.

Hussam Ayloush, the executive director of the Greater Los Angeles Area office of the Council on American-Islamic Relations, said in an interview on Thursday that it was unclear what had prompted Mr. Alnaji’s arrest.

“He’s a professor, not a violent person,” Mr. Ayloush said of Mr. Alnaji, a father of three. “Even the sheriff’s department has said he has been cooperative from Day 1. He’s a family man, a community person, very kind, not a violent person. This seems to have been one of those very unfortunate accidents that led to a terrible, terrible ending — a series of unfortunate events.”

Mr. Alnaji has been placed on administrative leave as a professor of computer science at Moorpark College, the Ventura County Community College District said on Thursday. Requests for interviews were declined last week and on Thursday at his home in a quiet cul-de-sac in Moorpark.

Mr. Kessler, a father of two children who worked in the medical supply industry and flew planes as a hobby, lived just seven miles south. A woman who lives on his block said last week that the neighborhood was “really broken up about this” and asked for respect for their grief.

He attended Temple Etz Chaim in Thousand Oaks, a Conservative synagogue that hosted a night of healing last week. A few hundred people came in person, while several thousand watched online, according to Ari Averbach, the senior rabbi.

“The clergy of our area is pretty close, so we’ve been talking to each other, we’ve been emailing, we’ve had meetings,” Mr. Averbach said. “And hopefully we’re on the same page that if a community member of any of ours is killed at the hands of somebody who is filled with hate, that’s a moment of tragedy for our entire community.”

Reporting was contributed by Shawn Hubler, Jill Cowan, Victor Mather and Sergio Olmos.