The Utah man -- accused of making a bomb threat, against the Salt Lake City Marathon -- has sent a letter of apology to organizers.
However, terrorist threat charges remain in place, against George Zinn, 59, of Salt Lake.
Police claim Zinn sent an email -- to members of the marathon's marketing department -- asking for help in planting bombs at the finish line.
The email was allegedly sent, just days after the Boston Marathon bombings.
Zinn claims the email was a "joke."