Trump hush-money Judge Juan Merchan under heightened protection at the Manhattan courthouse where he sits

• Judge Juan Merchan is being protected with increased security in the wake of Trump's NY indictment.
• Merchan also presided over the Trump Organization trial that recently ended in convictions.

Security at Manhattan Criminal Court and around the judge assigned to the criminal case against Donald Trump has been heightened in the wake of the grand jury's vote on Thursday to indict the former president.

Court officers at 100 Centre Street closed the 15th floor of the courthouse — where Manhattan Supreme Court Justice Merchan has his courtroom — to members of the press and public Friday.

Merchan continued to hear cases, with 10 on his daily docket, but court officers holding clipboards stopped people from exiting an elevator on that floor. Only lawyers and defendants in his scheduled cases were allowed on the floor.

There's been added security around the building… they closed off the back entrance," one lawyer, Andrew Miller, told Insider Friday.

Miller said there's some increase in security but it's akin to what he's seen before on high-profile cases.

Merchan's security has been high since Thursday evening, after the grand jury voted to indict. Merchan returned to the courthouse at around 7 p.m. to sign a document allowing District Attorney Alvin Bragg to disclose the existence of the indictment.

The document was signed in a sealed courtroom and under heavy court-officer guard. Reporters from Insider and other news outlets were not allowed to observe.

Shortly after the document was signed, Bragg announced that Trump had been indicted.

On Friday morning, Trump posted a rage-filled Truth Social post attacking Merchan, who has a history of overseeing high-profile political trials.

In addition to being the judge assigned to Trump's criminal case, Merchan previously presided over the Manhattan fraud trial involving the Trump Organization and its former CFO, Allen Weisselberg, as well as a fraud and money-laundering case involving ex-Trump advisor Stephen Bannon.

"The Judge "assigned" to my Witch Hunt Case, a "Case" that has NEVER BEEN CHARGED BEFORE, HATES ME," Trump wrote. "His name is Juan Manuel Marchan, was hand picked by Bragg & the Prosecutors, & is the same person who "railroaded" my 75 year old former CFO, Allen Weisselberg, to take a "plea" deal."

Weisselberg reluctantly testified for the prosecution last year in the Trump Org case, as part of a plea deal that sent him to jail for five months.

Throughout the day on Friday, members of the NYPD and other law enforcement agencies moved in and around the courthouse.

Trump is expected to surrender to authorities and be arraigned at the courthouse on Tuesday.

"The NYPD ensures thousands of events, including first amendment activities, are conducted safely in New York City each year," an NYPD spokesperson told Insider in a written statement. "Officers have been placed on alert and the department remains ready to respond as needed and will ensure everyone is able to peacefully exercise their rights. There are no current credible threats to New York City."

Miller said a judge told him Friday that he shouldn't expect to work on Tuesday afternoon.

"I gather that it's going to be all hands," Attorney Andrew Miller said of the security during Trump's arraignment.