First son-in-law Jared Kushner, whose security clearance is currently under probe by lawmakers, “continues to use” WhatsApp and his personal email to conduct government business, and former Deputy National Security Adviser K.T. McFarland used her AOL account to do the same, even discussing the transfer of “sensitive U.S. nuclear technology to Saudi Arabia,” according to information handed over to the House Oversight and Reform Committee by Kushner attorney Abbe Lowell, the committee’s chairman, Rep. Elijah Cummings, D-Md., wrote in a letter Thursday to White House Counsel Pat Cipollone.

During a meeting with Lowell, the attorney “confirmed that Mr. Kushner has been using the messaging application WhatsApp as part of his official White House duties to communicate with foreign leaders,” Cummings wrote. “Mr. Lowell could not answer whether Mr. Kushner’s communications included classified information – which would be a major security breach – but instead directed the Committee to inquire with the National Security Council and the White House.”

Kushner’s use of personal email and WhatsApp could be a violation of the Presidential Records Act, which the committee chairman said prohibits senior officials in the White House “from creating or sending a record ‘using a non-official electronic message account’ unless the employee copies his or her official email account or ‘forwards a complete copy’ to the official email account ‘not later than 20 days’ after sending or receiving the original email.”

Lowell took issue with Cummings assertions, saying that he did not say Kushner’s “communications through any app was with foreign ‘leaders’ or ‘officials,’” but rather that the presidential adviser had “used those communications with ‘some people’” and had not specified who they were.

In the letter, Cummings expressed frustration that the White House hadn’t yet “produced a single piece of paper to the Committee in the 116th Congress – in this or any other investigation,” contending that the “failure to provide documents and information is obstructing the Committee’s investigation into allegations of violations of federal records laws by White House officials.”

He gave the White House until April to “comply voluntarily” with the committee’s entreaties or the panel will be compelled to “consider alternative means to obtain the information it needs to conduct its investigation.”

This is not the first time Kushner has been called out for use of personal email and encrypted messaging apps. For instance, he and wife Ivanka Trump reportedly used a private email server for government business, and Cummings in his letter reminded White House counsel of the numerous times lawmakers have requested clarification of and information about Kushner’s communications practices.

On the campaign trail to the presidency, then-candidate Trump assailed his opponent, Hillary Clinton, for her use of a private email server while serving as Secretary of State, contending she compromised national security. As a candidate and then after gaining the White House, Trump continued to raise the issue, and the rallying cry “lock her up” became a mantra at his rallies.