NEW YORK (Reuters) - Health insurance companies are reassessing the risks for their top executives after the murder of UnitedHealthcare CEO Brian Thompson on Wednesday in Manhattan, with both UnitedHealth ( UNH ) and rival CVS Health ( CVS ) removing photos of their leadership teams from their websites after the shooting.

UnitedHealthcare, part of UnitedHealth Group ( UNH ), is the biggest U.S. insurer. CVS operates Aetna, another top insurer.

Thompson was killed in an attack police called targeted as he was about to enter the Hilton hotel for the company's annual investor conference. The gunman, whose crime was recorded on video, is at large and the New York City Police Department said there was no known motive for the murder.

Robert D'Amico, founder of Sierra One Consulting, who previously worked with the FBI, said the removal of photos showed, "These companies are hearing what experts like me have been saying about how easy it is to identify and then find their executives."

UnitedHealth ( UNH ) took down Thompson's and other executives' photos from its website on Wednesday. A spokesperson did not respond to a query asking what the motivation was. CVS removed pictures of all its top executives on Thursday. The company declined to comment.

D'Amico and a second security expert, who said they are constantly assessing risk for top executives based on news events or the business their companies conduct, expect companies to ramp up physical security for executives.

The healthcare sector in the last 18 months has explored new security measures as they encountered increasing conflict and the potential for violent crime, said Glen Kucera, president of Enhanced Protection Services at security firm Allied Universal.

Before the shooting, most risk assessment efforts were conducted for medical practices and other healthcare providers, which have faced increasing hostility from the public since the COVID-19 pandemic.

Rising demand for protection in hospitals and healthcare facilities is in line with most customer-facing industries, said Garett Seivold, chief content and communications officer at the International Security Ligue.

Assessing risk involves searching social media and trying to determine whether threats have been made, circumstances which have not been made public regarding Thompson, Kucera said.

Thompson's wife, Paulette, told NBC News on Wednesday that he had been receiving some threats related to his job and "coverage" but said she did not know the details. A spokesperson for UnitedHealthcare did not have an immediate comment on possible threats against Thompson.

"I think there's going to be a lot of executives that are going to say, 'Hey, you know, this could happen to me and we should really consider our security protocol going forward,'" Kucera said.

D'Amico said he expects corporate boards of directors to reassess their security plans for executives.

That would include asking for assessments on how big a security detail to deploy while weighing the cost. Someone like billionaire Elon Musk has 20 people around them every day, he said.

He pointed to angry social media posts which appeared to show people verbally attacking health insurance companies and employees in the immediate aftermath of Thompson's murder.

   "I think the healthcare companies are going to see that and realize that there's more hate out there for them and their executives," D'Amico said.

Consumer frustration with health insurance in the U.S. has been high for years and led to the 2010 Affordable Care Act, popularly known as Obamacare. This year, insurance companies have struggled to hold down costs and have talked about their increased use of medical management, which includes making it more difficult to quickly receive coverage for services like surgery or medicines.

   It is not known whether Thompson's job played any role in his death, but the shooting has brought attention to increasing tension with the healthcare industry.

Cigna, Elevance, Centene and Molina did not respond to requests for comment about whether they were making any security changes now or had done so.

Health insurers do not provide details on their spending on security for executives in financial regulatory filings.