Court documents say 34-year-old Vikings fan Ty Copp had been trading "good-natured joking" with Seahawks fans sitting near him and his wife throughout the game.
With the Vikings losing the Nov. 4, 2012 game, Copp and his wife got up to leave towards the end of the game to beat traffic and exchanged a few more jokes with other fans, when William D. Van Meveren allegedly "sucker-punched" him, according to a detective who filed the assault report.
The blow knocked Copp unconscious, and he fell backwards and hit his head on the cement as he toppled down the stairs.
Copp suffered a fractured nose, concussion, lacerations and abrasions. He reportedly continued to experience tingling and numbness from his neck to his hand months after the assault.
Several witnesses identified Van Meveren and police arrested him without incident at the stadium. He claimed someone threw a punch at him first. He is scheduled to make his first court appearance Sept. 9.