Interviews with more than a dozen lawyers and officials involved in aspects of the Russia probes hint at the intensity of what lies ahead in an investigation the president continues to rail against as “fake news” and a “witch hunt.”

That intensity is intended to put a strain on major characters as well as bit players who are under investigation, as they jockey for advantage and it becomes clearer who is cooperating with investigators and who is resisting.

“In any criminal investigation it is in the government’s interest to magnify conflicts between the various people they’re looking at,” said Renato Mariotti, a former federal prosecutor who’s now a partner at Thompson Coburn LLC. “When the subjects of an investigation are pitted against each other the government can exploit those conflicts to induce some of the individuals to cooperate against others.”

Although much of what Mueller is doing remains secret, there have been signs recently that his investigation is expanding, said two US officials. That includes issuing subpoenas to a former lawyer and current public relations spokesman for Manafort, whose Virginia home was raided by the Federal Bureau of Investigation (FBI) last month.

Manafort, who directed Trump’s campaign during six critical months last year, has emerged as a central figure because of his past financial dealings and his work for a Russian-backed party in Ukraine.

Manafort’s financial transactions are also under scrutiny by New York’s attorney general, Politico reported, adding the former campaign chairman has not been accused of any wrongdoing.

Attorney General Jeff Sessions, who earned Trump’s ire when he recused himself from the Russia probe, is also expected to testify in the Senate in the coming weeks for the second time since his January confirmation hearing. While Sessions may want to focus on his anti-crime agenda, senators will demand details about his role in firing Comey, who had led the Russia probe.

“The investigations are becoming more active,” Mariotti, who led prosecutions in a range of white-collar crimes including securities fraud and tax evasion, said in an interview. Mueller is “conducting an extremely thorough and wide-reaching investigation into what are complex crimes” while Congress is holding hearings and releasing details that Mueller might not, he added.

Mueller also will submit a list of his expenditures to the Justice Department soon after September 30, which may provide insight into the scope of his investigation. The department is expected to make the document public.

Besides Manafort, one focus of investigators on Capitol Hill is the president’s eldest son.

Donald Trump Jnr has come under scrutiny for arranging a meeting in June 2016 with Russians who were promising damaging material on Trump’s rival, Hillary Clinton.

With congressional committees competing to hear from key witnesses, the Senate Judiciary Committee appears to be first in line to hear from Donald Jnr, though no firm date has been set.

“In late July, Donald Trump Jnr agreed to provide the Judiciary Committee with documents and a transcribed interview prior to a public hearing,” Judiciary Chairman Chuck Grassley and the panel’s top Democrat, Dianne Feinstein, said in a joint statement on August 29. “Shortly thereafter, a date for that interview was set and agreed to by both the committee and Trump Jnr.”

The Judiciary Committee also might vote this month on whether to release a transcript from a 10-hour closed hearing in August with Glenn Simpson, founder of the political consulting firm Fusion GPS that helped create a dossier with salacious and unverified material about Trump.

“The committee has a transcript of the interview,” Simpson’s lawyer, Joshua Levy, said in a statement. “We are not permitted to have a copy. The committee has the right to disclose the transcript, if it wishes to do so.”

The House Intelligence Committee issued subpoenas in June seeking testimony and documents from Trump’s personal lawyer Michael Cohen, as well as Trump’s former national security adviser Michael Flynn. Flynn was removed after lying about communications he had with Russia’s then-ambassador to the US, Sergei Kislyak, before Trump took office.

Cohen has come under scrutiny because of allegations about him contained in the dossier linked to Fusion GPS and made public in January.

Cohen’s lawyer, Stephen Ryan, sent the House Intelligence Committee last month a point-by-point rebuttal of what he described as “sensational allegations” contained in the 35-page dossier. Ryan’s letter described that document’s allegations of ties between Cohen and Russian officials as false.

Cohen confirmed in an interview that he will testify before the House panel in September, after which he plans to testify before the Senate Intelligence Committee. He added that he has not received any communication from Mueller and has not been asked to appear before a grand jury.

Trump’s son-in-law, Jared Kushner, was interviewed behind closed doors by the Senate and House intelligence committees, on July 24 and 25. Since then, Kushner has not received any requests to testify in private or public before any congressional committee, according to a person with knowledge of the matter. He also has not received any formal requests or subpoenas from Mueller’s team, the person said.

But Democrats said they continue to focus on details surrounding a meeting Kushner had in December, a month before Trump took office, with Sergei Gorkov, the head of a Russian state-owned bank known as Vnesheconombank, according to Representative Adam Schiff, the intelligence panel’s top Democrat.

Schiff cited the bank’s “reported ties to the Kremlin, that the meeting was taken at the request of Russian Ambassador Kislyak, and that Gorkov is a graduate of the FSB’s finishing school,” a reference to Russia’s premier spy agency.

“These are not normal times and things are about to heat up” for Trump and his associates, said Jeffery Cramer, a former federal prosecutor. “The clock is ticking.”