MIAMI, Florida (AP) — Former United States President Donald Trump and his aides are bracing for a potential indictment in the classified documents investigation as prosecutors handling the probe were spotted Thursday at a Miami courthouse where a grand jury has been hearing from witnesses.

The former president’s lawyers have been told he is a target of the investigation — the clearest indication yet that criminal charges could be coming soon, according to two people familiar with the matter.

In an effort to get ahead of a potential indictment, Trump aides, over the last two days, have been reaching out to his allies in Congress to be prepared to go on television and offer defences of the former president, according to another person familiar with the matter.

The people spoke on condition anonymity to discuss matters related to the secretive grand jury process.

Meanwhile, a grand jury in Miami heard from at least one additional witness this week — a former top aide to Trump — as signs continued mounting that prosecutors were building toward a potential indictment related to the handling of hundreds of classified documents at Trump’s Florida home, Mar-a-Lago.

On Monday, his lawyers met with Justice Department officials in Washington to argue against an indictment, exiting the building stone-faced less than two hours later without commenting. Trump, meanwhile, has issued social media posts this week suggesting he anticipates being charged and has escalated attacks on special counsel Jack Smith and his team.

A key prosecutor on the team, David Harbach, was spotted by an Associated Press journalist outside the courthouse on Thursday.

The notification to Trump’s lawyers that he is a target is especially ominous given that such a warning often, though not always, precedes criminal charges. The Justice Department defines a target as someone whom prosecutors have substantial evidence linking to a crime.

“The signal is increasingly that the charges against the former president will be in Florida,” said Brandon Van Grack, a former Justice Department prosecutor and a key lawyer on an earlier special counsel team that investigated ties between Russia and the 2016 Trump campaign.

Lawyers for Trump did not return calls seeking comment. A Trump spokesman would not confirm or deny receiving a letter and a Justice Department spokeswoman declined to comment.