One evening in December on a desolate backstreet in Indore, robbers held up a motorcyclist, threatened him at knifepoint and made off with the takings he was carrying to his boss. Solving such crimes is often tricky, but with the help of footage from private CCTV cameras in the area, police were able to track down the culprits and recover the stolen Rs 1 million within hours. They used Citizen Eye, a feature on the mobile app CitizenCOP that allows city residents who have CCTV cameras watching over their homes or businesses to give police access to the footage to...