FBI worried that Ring doorbells are spying on police
Hacked documents suggest that the FBI is concerned some people may be using Ring or other smart doorbells to watch the police.
The papers describe a 2017 incident where someone remotely watched live footage of police preparing to serve a search warrant.
The information was found online by The Intercept among hacked documents.
Previously, privacy advocates have raised concerns about data from smart doorbells being shared with police.
The hacked papers, known collectively as BlueLeaks, were stolen from more than 250 police websites.
The document in question is a technical analysis bulletin, offering an overview of the opportunities and challenges for police from home security systems and smart doorbells.
The 2017 incident describes how someone under investigation was able to "covertly monitor law enforcement activity while law enforcement was on the premises" and alert his neighbour and landlord. It does not name the brand of video doorbell used.
Amazon's Ring is one of the most popular, but there are a variety of companies selling smart doorbells along with home surveillance kits.
It is an interesting twist on the smart doorbell story. Previously there have been concerns about how much information from private cameras is being shared with police.
Amazon was criticised last year for partnering with at least 200 US law enforcement agencies to allow police officers to ask customers to share videos and information about crime in their areas.
At the time digital rights group Fight the Future said it "undermined our democratic process and basic civil liberties".
In the UK, Wiltshire police have set up a database of private smart doorbells and security cameras, and residents are being asked to register theirs.