Amnesty International report that Rio de Janeiro police kill more than 400 civilians a year - one of the highest rates in the world. Police are almost never charged, let alone convicted.
New York techies Harlo Holmes and Nathan Freitas are developing a smartphone app so media activists in Rio de Janeiro, like Colectivo Papa Reto, can securely document police violence.
A group of citizen journalists and a human rights organisation join the coders, Holmes and Freitas, as they beta test an app called CameraV.
This app captures key metadata about a given moment and embeds that data into the image's pixels. The app developers are effectively putting the power of metadata back into the hands of the people by hacking the smartphone's key sensors, so that citizens can record events and hold those in power accountable.
