Former House staffer tells '60 Minutes' White House switchboard called Capitol rioter on Jan. 6

• Denver Riggleman, who studied calls Jan. 6, found one from the White House switchboard.
• Riggleman said he didn't know who placed the call, but he does know who received it.
• The revelation comes days before the next committee hearing Wednesday.

WASHINGTON – The White House switchboard called one of the rioters on Jan. 6, 2021, a former House staffer told CBS's "60 Minutes."

Denver Riggleman, a former U.S. House of Representatives member from Virginia, military intelligence officer and senior technical adviser to the House panel investigating the Capitol attack, said he knows who received the call, but not who placed it. He didn't name the rioter in an excerpt released by "60 Minutes," which will air Sunday.

"From my perspective, you know, being in counterterrorism, you know, if the White House, even if it's a short call, and it's a connected call, who is actually making that phone call?" Riggleman asked.

While working for the committee, Riggleman analyzed call records, texts and online activities of hundreds of people suspected of playing roles in the attack. He called the discovery of the call a "pretty big 'aha' moment."

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He spoke with "60 Minutes" to promote the publication of his book "The Breach." The program released an excerpt Friday.

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Riggleman's interview also appeared before the committee holds another hearing Wednesday at 1 p.m. ET.