The House panel investigating the Jan. 6 insurrection at the Capitol has identified a roughly eight-hour gap in official records of then-President Donald Trump's phone calls as the violence unfolded and his supporters stormed the building, according to a person familiar with the probe.

The gap extends from a little after 11 a.m. to about 7 p.m. on Jan. 6, 2021, according to the person, who was not authorized to speak publicly about the ongoing investigation and spoke to The Associated Press on Tuesday on the condition of anonymity.

It's widely known that Trump had conversations on Jan. 6 with multiple Republican lawmakers. House investigators are looking at whether the president was communicating during that time through other means, possibly through personal cellphones, burner phones or some other type of communication — like a phone passed to him by an aide. The committee has subpoenaed cellphone companies for records and is awaiting data.

The committee is also continuing to receive records from the National Archives and other sources, which could produce additional information.

But the lack of information about Trump’s calls is a frustrating challenge to investigators as they work to create the most comprehensive record yet of the attack, with a particular focus on what the president was doing in the White House as hundreds of his supporters violently beat police, broke into the Capitol and interrupted the certification of Democrat Joe Biden’s presidential election victory. It also raises questions of whether Trump purposefully circumvented official channels to avoid records.

During the missing hours, Trump went to the rally at the Ellipse, spoke, then watched as the violent mob broke into the U.S. Capitol, overwhelming police and marauded through the building for hours before they were finally kicked out and the building declared secure at about 5:30 p.m. More than 700 people have been arrested in the violence.

The gap in records was previously reported by the AP. The exact length of time of the gap was first reported by The Washington Post.

The committee is focused on Trump’s actions that day because he waited hours to tell his supporters to stop the violence and leave the Capitol. The panel is also interested in the organization and financing of a rally that morning in Washington where Trump told his supporters to “fight like hell.” Among the unanswered questions is how close organizers of the rally coordinated with White House officials.

In many cases, the committee may not need direct confirmation from the White House about Trump’s calls. Lawmakers have already interviewed more than 500 witnesses, including several people in Trump’s inner circle who may be able to fill in those gaps. They are hampered, though, by the former president’s claims of executive privilege over his personal conversations, which have prompted many witnesses to refuse to answer some questions.

For example, committee members voted unanimously on Monday to hold former Trump advisers Peter Navarro and Dan Scavino in contempt of Congress for their monthslong refusal to comply with subpoenas.