Last spring, dispatchers at Los Angeles International Airport received an anonymous call suggesting that a Spirit Airlines flight bound for Las Vegas would “explode.”

In April, a staff member at a legal clinic received a call from someone threatening to bring a grenade into the office if the lawyer did not contact him.

Then, in early October, someone reported a bomb inside LA City Hall.

Both were serious threats made by the Los Angeles Police Department over the past year and a half. And, as subsequent investigation revealed, the whole thing was a hoax. The difference between the City Hall case and the other two cases is that authorities announced they were investigating Brian Williams, Mayor Karen Bass’ chief of staff, on suspicion of false claims.

The revelation received a variety of reactions on the internet, from understandable ridicule to “Maybe he took a test he didn’t study for?” — to the shock expressed by City Hall and LAPD officials who said in private conversations that the charges did not match the man they knew.

Law enforcement experts say such threats are common and tend to increase around major social events, such as national elections. Examples of spikes in reports of suspicious bags and items occurred in the aftermath of major incidents, such as the 1995 Oklahoma City bombing, when authorities were inundated with calls from a newly alarmed public.

Even if the report appears to be a hoax, authorities cannot take any chances and must investigate each case one by one, by removing buildings and bringing in explosive-sniffing dogs.

Los Angeles Police Department records show the department has investigated numerous bomb threats at government offices, schools and sports stadiums, including at least 144 where police found explosives. There were 34 such incidents last year, tied for the most in at least five years.

The growth of privacy-oriented technology and social media can make it difficult to identify the source of a threat.

On Thursday, the day after news broke about Williams, there was a festive atmosphere at City Hall, with long lines forming in front of the Christmas tree in the rotunda for photos with the mayor. But behind closed doors, many government officials continued to speculate about the allegations against Williams.

Questions remain about when LAPD investigators first became suspicious that Williams might be involved, and when they notified department leaders and Bass’s office of the investigation. Williams’ attorney said he is innocent and “intends to vigorously fight the charges.”

The bomb threat was made in the first week of October, said two people familiar with the allegations, who asked not to be identified because they were not authorized to speak publicly about the ongoing investigation.

As is often the case in federal investigations, authorities are tight-lipped, and an FBI spokeswoman declined to comment.

Federal agents searched Williams’ home on Tuesday, according to a statement released by Bass’s press secretary.

In a separate statement, the Los Angeles Police Department identified Williams as the “possible” source of the threat.

Mr. Williams has been placed on administrative leave pending the outcome of the investigation.

“Importantly, he has not been arrested or charged and will continue to cooperate with the investigation through his attorney,” Williams’ lawyer Dmitry Gorin said.

If the allegations are true, several city officials have described him as a soft-spoken, smartly dressed colleague who has never shown any anger or impulsive behavior on the job. The allegations would mark a surprising turning point for a public servant who was respected and widely liked. .

Mr. Williams has held various government positions for more than 30 years.

He spent nearly two years in Bass’s office as deputy mayor, working on a wide range of issues from police hiring to public safety spending. He was also one of the mayor’s trusted aides during the months-long search for a new police chief, which ended with the appointment of Jim McDonnell in early October.

Mr. Williams served as Deputy Mayor in the administration of Mayor James K. Hahn, who served as Mayor from 2001 to 2005. Prior to that, he spent several years as an assistant city attorney in Los Angeles.

Williams served as executive director of the Sheriff’s Civilian Oversight Board from 2016 to 2023, according to his LinkedIn page. Williams worked in Bass’ office and oversaw the police department, fire department, port police, airport police and the city’s Office of Emergency Management, according to the hiring announcement.

In that role, Williams regularly attended police graduations, press conferences, community meetings and other events around the city, often wearing a neat press suit and bow tie. The distance is atti. Nathan Hockman was sworn in this month, and Williams was selected as the city clerk to address the audience on the mayor’s behalf.

Some in the city’s black political and religious communities rallied behind Mr. Williams, issuing statements of support and disbelief. A rally for supporters is planned outside the 77 venue on Friday morning.^th South Los Angeles Police Department

Most bomb threat cases are handled by the Major Crimes Division’s Criminal Conspiracy Unit, which also investigates bombings, complex arson, and suspects in possession of bomb-making materials.

In the past few years, investigators with the unit have sought search warrants for access to phone and email records to get to the bottom of bomb threats, usually searching for suspects who have tried to hide their identities. are.

In one such incident, serious crime detectives launched an investigation after someone on social media platform X posted that a bomb had been planted at No. 45.^th It was located on a high floor downtown and was tagged with an LAPD account. This firm is home to the Louis Brisebois law firm.

A similar threat was made against Inner City Law Center about a month ago, when someone sent a fax to the office and a specific employee said, “If you don’t call this number back by the end of today, , take a grenade inside.” City law, please take action as soon as possible. ”

Major crimes investigators executed a search warrant on the social media user who allegedly made the post, and found the Gmail address associated with the account.

In the incident at Los Angeles International Airport last year, police said a dispatcher received an anonymous call stating that the 1045 Spirit Airlines flight at Gate 56B to Las Vegas was about to explode. The dispatcher reported the report to airport police, who searched the area but found nothing.

Major crime authorities determined that the calls were made through TextNow, an app that lets users anonymously send text messages and make phone calls, and ordered the company to submit information about its subscribers. I asked for it.

Officials say the majority of bomb threats remain unsolved.

Simon Osamo, founder of Kingswood Security, a risk management consulting firm in Minneapolis, said police are fighting hoax bomb attacks and so-called swatting, where individuals make false 911 calls to induce an armed law enforcement response. He said that the number of responses is increasing.

The Los Angeles Police Department’s response to such incidents at the homes of public figures has come under scrutiny in recent years, including criticism of the city’s aggressive response to an incident at the home of a Black Lives Matter leader in 2020. .

But in a country where mass shootings are tragically common, Osamoh said police tend to miss opportunities.

“In the modern society we live in, it’s very difficult for them to take a conservative approach,” Osamoh says.