WASHINGTON – Testifying before the House Intelligence Committee, former special counsel Robert Mueller said he wanted his office's report to be a "signal, a flag" to those with a responsibility to act.

Rep. Jackie Speier, D-Calif., had asked Mueller "on behalf of the American people," what lessons he wanted people to take away from the report.

"We spent substantial time ensuring the integrity of the report, understanding it would be living, a message to those who come after us," Mueller said. "But it is also signal, a flag, to those of us who have some responsibility in this area, to exercise those responsibilities swiftly and don't let this problem continue to linger as it has over some of the years"

More:'It is not a witch hunt.' Robert Mueller testifies on Trump and Russian election meddling in 2016

Mueller did not clarify, though, what "this problem" referred to.

Earlier Thursday, Mueller said his team had not made a determination on charging President Donald Trump.

He also said a president could be charged with crimes after leaving office, but did not say whether Trump should be charged. Mueller has defended the impartiality of his investigation, telling lawmakers the investigation was "not a witch hunt," despite Trump's insistence to the contrary.