The start of Mr Mangione's legal battles has prompted anonymous donors to chip in thousands of dollars towards his defence through online fundraisers.
It comes as some online have shared support for the suspect and anger at the health insurance industry. The New York City Police Department has also warned some healthcare executives are potentially in danger because of a "hit list" posted online after Mr Thompson's murder.
In a bulletin, the NYPD said several viral posts included the names and salaries of other insurance executives. Mocked-up wanted signs featuring some executives have also been posted in Manhattan.
Mr Mangione allegedly had grievances with the wider industry.
Timothy Gallagher, a former FBI agent and the managing director of Nardello and Co, a global investigations firm, said the current climate means the "threat of a copycat is real".
"There are people out there who have grievances and are observing the amount of press and attention that is being given to the accused," he said.
Mr Gallagher said that there has been an "outpouring of support from dark corners of the internet" for anti-corporate causes.
"I'm afraid that may fuel follow-on attacks," he said.
