A member of the US Marshals Service walks in front of the federal district court in Miami, Florida in 2018.
CNN  — 

The head of the US Marshals Service is sounding the alarm on a dramatic increase in the number of threats aimed at federal judges and prosecutors, telling lawmakers on Wednesday that the development “constitutes a substantial risk to our democracy.”

“I’m deeply concerned with the alarming increase in threats against our judiciary and the violent nature of those threats. In the past three years, the number of threats against federal judges have more than doubled, as have threats against prosecutors and other court officials,” US Marshals Service Director Ronald Davis told a House Judiciary subcommittee.

“I must state in stark terms that the current and evolving threat environment facing the judiciary constitutes a substantial risk to our democracy,” Davis added.

The number of federal judges who received serious threats rose to 457 in the fiscal year 2023 that ended in September, up from 300 the year before and 224 in fiscal 2021.

The number of federal prosecutors who were targets of threats also more than doubled from 68 in fiscal 2021 to 155 in the last fiscal year, according to data from the US Marshals Service.

These were threats considered serious enough to warrant an investigation by the Marshals Service, which is responsible for protecting federal judges and court staff.

The threat environment has worsened amid a politically divisive time in the United States.

A number of threats have been aimed at court officials connected to cases against Donald Trump, including from a Texas woman who was recently sentenced to three years in prison after leaving three threatening voicemails for the judge in Florida who is overseeing the criminal case against the former president over his handling of classified documents.

Judges overseeing court cases against Trump in New YorkColorado and Washington, DC, also has been threatened, according to reports and officials.

Judge Tanya Chutkan, who is presiding over Trump’s federal election subversion case in DC, has been the subject of at least one racist threat and a swatting incident, which are dangerous prank calls made to authorities to lure them to a location under the false pretense that a crime has been committed or is in progress.

Chutkan has received a significant increase in protection since being assigned Trump’s case last summer.

In another high-profile case, a California man was charged in 2022 with attempting to kill Supreme Court Justice Brett Kavanaugh after law enforcement arrested him near Kavanaugh’s home outside of DC with a bag containing a gun and burglary tools, according to officials.

The man, Nicholas Roske, had called 911 on himself and later told law enforcement he was upset over the leaked draft Supreme Court opinion on abortion rights, among other issues, and had travelled to Maryland to kill a justice, according to officials. Roske has pleaded not guilty, and in recent court filings his attorneys say they are in talks with prosecutors “regarding a pretrial resolution.”

CNN’s Devan Cole contributed to this report.