John Eastman, who was in the vanguard of lawyers plotting schemes involving “fake electors” and other ploys to help Donald Trump thwart Joe Biden’s win in 2020, is now under close scrutiny in federal and state investigations of Trump’s drives to stay in power, and faces possible disbarment in California, say former prosecutors.

The former California law professor is one of several lawyers whose legal stratagems have been heavily examined by Special Counsel Jack Smith’s accelerating investigation into Trump and his allies’ efforts to block Biden from taking office.

The fake electors scheme was a central part of Trump’s strategy to reverse his defeat.

It was called that because Republican electors in seven key battleground states signed certificates falsely declaring themselves “duly elected and qualified” to affirm Donald Trump won the 2020 election.

But Eastman has drawn scrutiny too in an overlapping inquiry in Georgia by Fulton county district attorney Fani Willis, who is expected to bring criminal charges in August against Trump and some of his legal gurus.

The federal and Georgia inquiries have zeroed in on Trump legal advisers including Rudy Giuliani, who helped oversee the fake electors plot, and ex-justice department official Jeffrey Clark. Trump tried briefly to elevate Clark to attorney general in order to prod Georgia and several other swing states to substitute fake Trump electors for ones Biden actually won.

Smith’s inquiry, which encompasses Trump’s inflammatory talk to a rally that Eastman and Giuliani also addressed before the Capitol attack on January 6, has accelerated with grand jury testimony from former vice-president Mike Pence and ex-chief of staff Mark Meadows. Smith has also gained cooperation from two Nevada fake electors who have testified before a Washington grand jury.

Moreover, investigators from Smith’s office interviewed Giuliani under a “proffer” arrangement, which does not preclude charges against him, seeking to ferret out details about the fake electors plotting and related schemes, as the New York Times reported.

Former DoJ prosecutors say Smith’s inquiry is making notable progress.

“The pace of activity in the special counsel investigation into the fake electors scheme seems to be quickening,” with significant cooperation from key witnesses and a focus on Trump’s top legal advisers, former DoJ prosecutor Michael Zeldin told the Guardian.

Other ex-prosecutors also see Smith’s inquiry gaining steam.

“By obtaining testimony from fake electors, Smith may be better able to nail down what information and advice passed between these soldiers in the larger scheme and those Trump lawyers who helped to concoct it,” said Dan Richman, a law professor at Columbia and an ex-prosecutor in New York.

“Testimony that, say, electors were advised to make false statements or given deliberately misleading advice would go far to showing a deliberate fraud by Trump’s ‘brain trust’ of lawyers, including Eastman.”

Richman added: “Giuliani’s willingness to give a proffer likely reflects his desire to avoid charges by showing a lack of an intent to defraud. Smith’s readiness to accept the proffer likely reflects his interest in hearing what Giuliani had to say and avoiding a grand jury proceeding at which Giuliani might well invoke his fifth amendment privilege.”

Other DoJ veterans see Meadows’ grand jury testimony as significant. “The cooperation of Meadows has the potential to help put a stake in the heart of Trump and other high level insurrectionists,” said Paul Pelletier, a former acting head of the DoJ’s fraud section.

Smith, who was tapped as special counsel last November, and others at the justice department have spent months conducting their sprawling inquiry into Trump’s zealous efforts to cling to power, and his coterie of legal advisers. Last summer, federal agents seized the cell phones of Eastman and Clark, whose home was also raided.

A harbinger of the potential legal headaches for Trump and his elite lawyers came late last year when a House panel that spent months investigating Trump and the January 6 insurrection and produced an 845-page report, referred Trump to the DoJ for prosecution, plus Eastman, Giuliani, Clark and lawyer Kenneth Chesebro.

The referrals did not mandate DoJ action, but provided substantial evidence against Trump and those lawyers.

The panel’s referral accused Trump of criminally engaging in “a multi-part conspiracy”, citing four specific crimes that seems to track what special counsel Smith is looking into: making false statements, obstruction of an official proceeding, conspiracy to defraud the United States, and aiding or comforting insurrection, all of which were referred to the DoJ for prosecution.

All four lawyers were referred for conspiring to defraud the United States. Except for Giuliani, the others were cited for conspiring to obstruct an official proceeding, referring to Congress certifying Biden’s win on 6 January.

The panel noted when Eastman addressed the “stop the steal” rally on January 6 he floated a wild conspiracy theory about “secret folders” in voting machines that were used to cast votes for Democrats.

The report also discussed a “coup memo” authored by Eastman which proposed avenues Pence could use to assist Trump in reversing his election loss, including unilaterally throwing out certain state electoral college votes.

At House panel hearings, Pence’s then counsel Greg Jacob testified that Eastman acknowledged to him that his push with Trump to get Pence to reject Biden’s winning electoral college count would violate the Electoral Count Act, and that Trump too was informed that if Pence tried to block Biden’s certification it would be illegal.

This June, Jacob testified at California bar hearings weighing disbarment of Eastman for making false public statements about voter fraud in the 2020 elections, and misleading courts. At the hearings, Jacob charged that Eastman’s advice to Pence “brought our profession into disrepute”.

Eastman has denied breaking any laws, stating that he was engaged in “good faith” advocacy on a legal question that was not settled. Trump and the other lawyers referred for DoJ prosecution have all also denied violating any laws.

But ex-federal prosecutor Paul Rosenzweig said he doubted Eastman will escape prosecution completely. “It will be surprising, indeed, if neither of those investigations ends in a criminal charge against Eastman, as well, possibly, as other lawyers and Trump himself.”

But more broadly, DoJ veterans say it is unclear exactly what charges Smith may bring.

“It remains to be seen whether the false electors scheme will serve as the basis of a standalone indictment or whether it will be merged into a broader case involving the multiple ways Trump and his allies attempted to reverse the outcome of the 2020 election,” former DoJ inspector general Michael Bromwich told the Guardian

“A standalone case may have less jury appeal than a case in which it is one of many sets of tactics used to overturn the election,” he added, but noted that “a broader case will almost inevitably be longer, more complex, include numerous defendants, and be more difficult to try.”

Any new federal charges against Trump would come on top of the 37-count indictment of Trump by Smith for retaining hundreds of classified and national security documents after he left office, and obstructing investigators seeking to retrieve them.

Trump has pleaded not guilty and denounced the charges and the other probes as “witch-hunts”.

Still, the Georgia inquiry into efforts to overturn Biden’s win there seems likely to create more headaches for Trump and some of his legal advisers. Willis has indicated that Giuliani, who testified after receiving a subpoena before a special grand jury, is a target of her broad inquiry. Eastman was reportedly advised by his own lawyer that he was probably a target and invoked the fifth amendment when subpoenaed to testify.

A key focus of Willis’s inquiry has been Trump’s high-pressure call on 2 January 2021 to Georgia secretary of state Brad Raffensperger, beseeching him to just “find” 11,780 votes to overturn his loss to Biden in the state. Willis’s scrutiny of Giuliani has looked at testimony he gave to Georgia legislators three times after Trump’s defeat, where he promoted discredited fraud claims and urged legislators to take action.

A once star federal prosecutor, Giuliani had his law licence suspended in New York and DC in the wake of his misguided legal efforts to help Trump.

Willis has said she will announce charging decisions in August, and experts say the Georgia inquiry looks poised to include criminal charges against Trump and some elite lawyers.

“Lawyers have a professional responsibility to tell the truth, and they may face legal liability when they don’t,” former US attorney in Georgia Michael Moore said.

“In the Georgia investigation, the intentional perpetration of a fraud, if borne out by the investigation, may land them in hot water. All indications are that the DA is looking at some lawyers as directors, not just bit players, in the story of attempted election fraud.”