"They have been very slow, though, on the much more comprehensive, and I believe, even more significant investigation of January 6," the California Democrat said here at the Texas Tribune Festival.
Schiff criticized the DOJ's overall strategy, saying he believes it was a mistake for the department to start its investigation from the ground up -- with those who broke into the Capitol -- because "that works when you have one plot, one conspiracy. It doesn't work when there are multiple lines of effort to overturn an election, multiple plots, that may be all part of the same whole, but nonetheless each operating independently."
"That may be changing too, but it's a long time coming" Schiff said.
"It would be equally breathtaking if we were to say to the Justice Department, 'Turn over all of your files,'" he said. "My first reaction when we got the request -- 'Turn over all your files to us' -- was: 'Why don't you have your own damn files? Why haven't you been conducting your own investigation? Why do you need us to do it?'"
Despite his criticism, Schiff acknowledged that the DOJ's investigation was ramping up, telling the crowd, "It does appear now that they have interviewed many of the same significant witnesses that we have."
The high-stakes legal dispute -- which included the appearance of three attorneys representing Trump at the Washington, DC, federal courthouse on Thursday -- is the most aggressive step taken by the former President to assert executive and attorney-client privileges in order to prevent some witnesses from sharing information in the criminal investigation into events surrounding January 6.