Leading up to Derek Chauvin's murder trial, Justice Department officials had spent months gathering evidence to indict the ex-Minneapolis police officer on federal police brutality charges, but they feared the publicity frenzy could disrupt the state's case.

So they came up with a contingency plan: If Chauvin were found not guilty on all counts or the case ended in a mistrial, they would arrest him at the courthouse, according to sources familiar with the planning discussions.

The backup plan would not be necessary. On April 20, the jury found Chauvin guilty on all three murder and manslaughter counts, sending him to the state's most secure lockdown facility to await sentencing, and avoiding the riots many feared could engulf the city once again.

Now, with Chauvin's state trial out of the way, federal prosecutors are moving forward with their case. They plan to ask a grand jury to indict Chauvin and the other three ex-officers involved in George Floyd's killing — J. Alexander Kueng, Thomas Lane and Tou Thao — on charges of civil rights violations, a source said.

If the grand jury voted to indict, the former officers would face the new civil rights charges on top of the state's cases, meaning all four could be headed toward yet another criminal trial in federal court.

The backup arrest strategy and meticulous planning over the timing of charges illustrates the complicated synchronicity of two parallel investigations into the most high-profile case of police brutality in decades. Over the better part of the last year, as special prosecutor Keith Ellison's team pursued murder and manslaughter charges, federal authorities have been mounting their own case in private before a grand jury — a group of 23 citizens who meet in secret to hear evidence and ultimately decide if there is probable cause to charge.