I'm interested in this too. And haven't been able to find much of anything.
> I am imagining an app that has a real-time, location-aware feed of media references to such instances to corroborate and publicize, potentially supported by facial recognition of offenders to gather evidence of repeat abuse.
I think the implementation and specific measures need careful consideration. Remember justice according to Rawls is a form of fairness among all members in society. What about the injustice going on that the police are tasked with stopping on a daily basis and their respective part in ensuring a just society? What about injustices against the police themselves? If we ignore such data points and issues, society will develop a false impression and injustice will supplant the justice we are striving for. IMHO any social justice software should be "context aware" in as broad a sense as possible (history of officers actions - good, bad, everything in between) and probably a history of the "offenders/recorders" public actions (again good, bad, everything in between) as well as specific encounters. Of course, this brings problems such as rights of privacy, among others.
A software which only captures specific encounters, and only makes them public when they are negative is something that on the whole might not be a net benefit for society. I'm unsure and I think it needs some consideration at the least.