Traitor or scapegoat? How one cop became the face of Jan. 6.

He was initially charged with the equivalent of trespassing, but T.J. Robertson has spent nine months in solitary confinement. His trial, scheduled to begin April 5, shows how the Jan. 6 Capitol assault reverberates among families and throughout America.

Samantha Robertson spots a broken railing on the front porch, and mentally adds it to an ever-growing list of chores for her husband to tackle when he comes home. Beneath the cracked rail is a neat line of men’s combat boots, unworn for the past nine months.

For much of the...