The FBI and local Colorado law enforcement are investigating threats made against the four Colorado justices who voted to keep former President Donald Trump off the state’s ballot in the 2024 primary election.

FBI Public Affairs Officer Vikki Migoya told CNN Monday that the bureau is “aware of the situation” and “will vigorously pursue investigations of any threat or use of violence committed by someone who uses extremist views to justify their actions regardless of motivation.”

The Colorado State Supreme Court ruled last week that for his actions on January 6, 2021, the GOP frontrunner violated Section 3 of the 14th Amendment, which prohibits individuals who have “engaged in insurrection or rebellion” from pursuing public office.

Just a day after the decision came down on December 19, a report from Advance Democracy, a nonpartisan, nonprofit research organization, found an increase in “significant violent rhetoric” targeting the justices online. Often, the violent posts came directly in response to statements from the former president on his social media site, Truth Social. Sometimes, the posts included email addresses, phone numbers, office addresses for the judges, and potential execution methods.

One post from a user on a fringe, pro-Trump website read that “all f— robed rats must f— hang,” appearing to reference the justices. Another said to “behead judges” and “slam dunk a judge’s baby into the trash can.”

“We are seeing significant violent language and threats being made against the Colorado justices and others perceived to be behind yesterday’s Colorado Supreme Court ruling,” the group’s president, Daniel Jones, told NBC. “The normalization of this type of violent rhetoric — and lack of remedial action by social media entities — is cause for significant concern.” Jones added that Trump’s own statements were “a key driver of the violent rhetoric.”

Last Thursday, the Denver Police Department responded to “what appears to be a hoax report” targeting one of the justice’s homes. The department reported that “everything checked clear, and we are continuing to investigate this report.” A spokesman told Axios Monday that DPD officers are “providing extra patrols around justice’s residences.”

The developments in Colorado are just the latest in a pattern of threats and harassment directed at judges, prosecutors, and other court employees involved in the various criminal cases against Trump. For months, Trump’s incendiary posts have raised security concerns, even as the current GOP frontrunner has been told on numerous occasions by federal officials to avoid rhetoric that might “incite violence or civil unrest.”

“You have Donald Trump, a former President of the United States, making vivid vitriolic personal attacks on prosecutors, on judges, calling them names, that adds gasoline to the fire into these chatrooms and people feel they are being called on,” CNN law enforcement analyst John Miller said on Monday.

“The problem is, for authorities, is sorting out the noise from who the real player is going to be, who might show up and do something.”