The U.S. special counsel probing Russian interference in the 2016 U.S. presidential election is accusing a London-based lawyer of lying to investigators about his contacts with Rick Gates, a former campaign aide to President Donald Trump, who had already been indicted in a money-laundering case linked to his lobbying efforts in Ukraine.

The office of Special Counsel Robert Mueller disclosed the accusations against attorney Alex Van Der Zwann on Tuesday, February 20, with the expectation that Van Der Zwann would plead guilty later in the day in a Washington court, Voice of America reported.

Read alsoGaddafi regime sponsored Tymoshenko campaign in 2010 – Arab mediaMueller's office alleges that the lawyer, while working for a law firm hired by the Ukraine justice ministry in 2012 to prepare a report on the trial of former Ukraine Prime Minister Yulia Tymoshenko, claimed that his last contact with Gates was in mid-August 2016. Tymoshenko had been convicted of embezzlement and abuse of power and imprisoned, but she later was cleared of charges.

The prosecutors contend that Van Der Zwann lied when he said he did not know why a September 2016 email between him and an unnamed person was not turned over to Mueller's office when he actually had deleted it. The criminal information filed against Van Der Zwann also alleges that he lied about his last communications with Gates and the unnamed person.

Gates and former Trump campaign chairman Paul Manafort were indicted in October over their consulting work in Ukraine for the Russian-backed government of one-time President Viktor Yanukovych, who was toppled in a popular uprising in 2014 and fled to exile in Russia.

Last week, Mueller indicted 13 Russian nationals and three Russian entities for conducting an illegal "information warfare" campaign to disrupt the 2016 U.S. election to help Trump win the White House. Mueller already has secured guilty pleas from former Trump national security adviser Michael Flynn and one-time foreign affairs adviser George Papadopoulos for lying to investigators about their contacts with Russia.