After another week of riveting testimony before the House Jan. 6 committee, it is natural to wonder: How many laws were broken, by whom, and will there be prosecutions? Some argue that former president Donald Trump is undoubtedly guilty of serious crimes and must be tried. Others insist that the criminal case against Mr. Trump still is not airtight, and that prosecuting a former president would tear apart the country. What is beyond doubt is that an intensive criminal investigation must proceed.