Race organizers have stepped up precautions in light of the events at this year's Boston Marathon.
The 48-year-old wants to qualify for Boston.
A strong international field will line up in The Windy City on October 13.
Bag check is the first thing that's been scrutinized.
He wasn't expected to walk again.
The two-time Olympian ran his first long road race last September -- and won.
Danni Allen lost 121 pounds to win the show's $250,000 grand prize.
But he's not hanging up his racing shoes.
Approximately 15,000 slots are up for grabs.
Announcement comes on same day that three Kenyan marathoners get banned for doping.