that the bullet only struck the brain's frontal lobe, which can absorb injury better, especially in the very young. >> less than 3 years old, the brain's ability to repair is truly remarkable. >> after a delicate 3 1/2 hour surgery, dr. moriarty was encouraged by comparison scans of erica's brain. the bullet and brain fragments in the pre-op image were gone. despite the repair, brain injuries are unpredictable and dr. moriarty urged caution. >> next few days in the icu would be critical. >> panning in now. another shell casing. >> at the crime scene, detective arnold continued to sift through clues. more leads came in to focus. a bloody footprint. three big red soda cans and two cigarette butts by the bed. >> the second one had an ash about an inch long. someone had left that cigarette and rushed out of there. >> detective arnold ordered dna testing on the cigarettes and