Where Jan. 6 prosecutions stand, 18 months after the attack

Eighteen months since a pro-Trump mob ransacked the Capitol and disrupted the peaceful transition of presidential power, prosecutors are closing in on another milestone: 900 arrests.

According to the latest Justice Department figures, more than 855 members of that crowd are facing charges that range from trespassing on restricted grounds to seditious conspiracy. Prosecutors estimate that more than 2,000 people actually entered the Capitol unlawfully that day, which means hundreds more arrests are likely in the months to come.

For a year and a half, the justice system has been...