The US attorney general, Merrick Garland, said he would “pursue justice without fear or favor” in his decision on whether to charge Donald Trump with crimes related to the Capitol attack and his attempt to overturn the 2020 election, as news reports indicate the justice department’s investigation is heating up.

The department is conducting a criminal investigation into the events surrounding and preceding the January 6 insurrection, an effort that Garland – speaking to NBC’s Lester Holt yesterday – called “the most wide-ranging investigation in its history”.

News reports suggested the inquiry is homing in on Trump’s role. The Washington Post reported – citing sources who spoke on condition of anonymity – that investigators had specifically questioned witnesses about Trump’s involvement in schemes to overturn the vote. The New York Times also reported that federal investigators had directly questioned witnesses about Trump’s efforts, signaling an escalation.

Meanwhile, Trump returned to Washington yesterday with a plea for police to be given “the respect that they deserve”.

• Can the House January 6 committee make a criminal referral? It can, but whether it should, or will, and whether it has presented sufficient evidence to do so, is a matter of extensive debate around the US and on the committee itself.