Sorry about the predator attack. I lost 3 hens in middle of day to a bobcat last year, and saw it coming back for the last body. Do you see any piles of feathers? Could some have escaped to hide? I would keep looking for them.
Crackles breathing can be moisture in the airway, which could be coming from the crop or injury to the lungs or air sacs. I would keep her in a quiet, dim spot where she is warm. Offer sips of water often if she is alert and able. A tsp of sugar per cup of water or electrolytes can help if she is in shock. Look for any hidden wounds or punctures under wings, back, and elsewhere. Clean any wounds with chlorhexidene and apply plain antibiotic ointment twice a day. Let us know how she is doing.