After Kirk’s Killing, Suspect Joked That His ‘Doppelganger’ Did It

The day after Charlie Kirk was killed, an acquaintance of Tyler Robinson’s posed a question to him in a group chat. The F.B.I. had just released two grainy surveillance images of a skinny young man in a cap and sunglasses walking in a stairwell on the Utah Valley University campus, and had asked for the public’s help in identifying the suspect. Tagging Mr. Robinson’s username on Discord, a messaging platform, the acquaintance attached the images and wrote “wya” — where you at? — with a skull emoji, suggesting that Mr. Robinson, 22, looked like the man being sought. Mr. Robinson...