DHS funds research and development for surveillance robots. It provides grant money by the hundreds of thousands to police agencies to buy their own. And sometimes it's bought and deployed robots -- for their skies, the ground and the waters -- of its own, usually concentrated along the border. It's not clear how many of those robots police operate, and law enforcement isn't by any means the only domestic market for the 'bots. But the trend lines point toward more robotic spy tools for law enforcement in more places -- with more DHS cash.