The House committee investigating the Jan. 6 attack on the Capitol has discovered gaps in official White House telephone logs from the day of the riot, finding few records of calls by President Donald J. Trump from critical hours when investigators know that he was making them.
Investigators have not uncovered evidence that any official records were tampered with or deleted, and it is well known that Mr. Trump routinely used his personal cellphone, and those of his aides, to talk with other aides, congressional allies and outside confidants, bypassing the normal channels of presidential communication.
But the sparse call records present a major obstacle to a central element of the panel’s work: recreating what Mr. Trump was doing behind closed doors during the assault on Congress by a mob of his supporters.
The gaps in the call logs were the latest in a string of revelations this week about the extent of Mr. Trump’s flouting of the rules and norms of presidential conduct, and how his penchant for doing so has left an incomplete record of how he operated while in office.
Some of the records that the Jan. 6 committee has received had been ripped to shreds and taped back together, reflecting the former president’s habit of tearing up documents. In addition, he removed more than a dozen boxes of presidential records from the White House when he left office, which the National Archives believes contained classified material, according to a person briefed on the matter.
The House Oversight committee on Thursday announced an investigation into what it called “potential serious violations” of the Presidential Records Act.
Mr. Trump has been loath to return the boxes of documents he took from the White House, despite repeated efforts by the National Archives to obtain them. At some point during a monthslong negotiation between Mr. Trump’s team and the agency, officials at the National Archives threatened to send a letter to Congress or the Department of Justice if he continued to withhold the boxes, according to a person familiar with private discussions, who spoke about them on the condition of anonymity.
And while he was president, staff in the White House residence periodically discovered wads of printed paper clogging a toilet — leading them to believe that Mr. Trump had attempted to flush documents, according to people familiar with the situation. He was known to do the same on foreign trips, the people said. (Those incidents are recounted in a forthcoming book, “Confidence Man,” written by a New York Times reporter, about Mr. Trump and his presidency.)
The highly irregular practices underscore the challenge of creating a full historical record of a presidency that often operated outside the bounds of longstanding rules.
They have also prompted accusations of hypocrisy from Democrats, who recall how Mr. Trump branded Hillary Clinton’s use of a private email server while she was secretary of state “worse than Watergate,” and made “lock her up” a campaign rallying cry in 2016. Republicans who eagerly followed his lead in savaging Mrs. Clinton for her email practices have been notably silent amid revelations that Mr. Trump spent his four years in office — and much of the time since — mishandling presidential records.
Counterintelligence officials say it is highly risky for presidents to use their personal cellphones, as those phones almost certainly have no protection against spying by foreign adversaries. There is nothing in federal record-keeping laws that explicitly addresses whether a president can use a personal cellphone for official business. But the spirit of the law is that presidents should avoid doing so — and if they do, their calls should still be memorialized, said Jason R. Baron, the former director of litigation at the National Archives.
“Government agencies are supposed to document phone calls when the conversation is about important government business,” said Mr. Baron, a professor at the University of Maryland. “A president choosing to use a personal cellphone on a sensitive matter of government business without the conversation being recorded anywhere raises serious questions about his compliance with the spirit” of the Presidential Records Act.