India, Nov. 12 -- Two days after a blast ripped through the heart of Old Delhi, killing at least 10 people and injuring dozens, investigators are piecing together the puzzle of what happened - and why. The Hyundai i20 car that exploded near the Red Fort on Monday evening has given rise to four key questions that now dominate the investigation: why that location, whether the blast was planned or accidental, if the detonator was hidden in the car's bonnet, and who exactly was inside the vehicle.

Why this location?

Perhaps the most pressing question is why the attacker chose the busy intersection outside Red Fort - one of the most tightly policed areas in Delhi. National Investigation Agency (NIA) officials are examining whether the explos...