Word of a growing partnership between police and the popular Amazon-owned doorbell camera company Ring is raising privacy concerns nationwide. Ring's "Neighbors" app lets customers know when and where a crime happens in their area. It works in conjunction with the so-called "Neighbors Portal," which Ring said Wednesday is now used by some 400 law enforcement agencies to request customer video. That might help their investigations.

"My goal would be to have every law enforcement agency on the police portal," Ring CEO Jamie Siminoff said. "It helps all communities come together to make things safer."

Andrew Ferguson, author of "The Rise of Big Data Policing," said there's a downside, though.