Police request Echo recordings for homicide investigation

You have the right to remain silent -- but your smart devices might not.

Amazon's Echo and Echo Dot are in millions of homes now, with holiday sales more than quadrupling from 2015. Always listening for its wake word, the breakthrough smart speakers boast seven microphones waiting to take and record your commands.

Now, Arkansas police are hoping an Echo found at a murder scene in Bentonville can aid their investigation.

First reported by The Information, investigators filed search warrants to Amazon (see below), requesting any recordings between November 21 and November 22, 2015, from James A. Bates, who was charged with murder after a man was strangled in a hot tub.

While investigating, police noticed the Echo in the kitchen and pointed out that the music playing in the home could have been voice activated through the device. While the Echo records only after hearing the wake word, police are hoping that ambient noise or background chatter could have accidentally triggered the device, leading to some more clues.

Amazon stores all the voice recordings on its servers, in the hopes of using the data to improve its voice assistant services. While you can delete your personal voice data, there's still no way to prevent any recordings from being saved on a server.

"It is believed that these records are retained by Amazon.com and that they are evidence related to the case under investigation," police wrote in the search warrant.

Amazon has not sent any recordings to the officers but did provide Bates' account information to authorities, according to court documents. The retailer giant said it doesn't release customer information without a "valid and binding legal demand."

"Amazon objects to overbroad or otherwise inappropriate demands as a matter of course," the company said in a statement.

Even without Amazon's help, police may be able to crack into the Echo, according to the warrant. Officers believe they can tap into the hardware on the smart speakers, which could "potentially include time stamps, audio files or other data."

The investigation has focused on other smart devices as well. Officers seized Bates' phone but were unable to break through his password, which only served to delay the investigation.

"Our agency now has the ability to utilize data extraction methods that negate the need for passcodes and efforts to search Victor and Bates' devices will continue upon issuance of this warrant."

Police also found a Nest thermostat, a Honeywell alarm system, wireless weather monitoring in the backyard and WeMo devices for lighting at the smart home crime scene.

Ultimately, it might have been information from a smart meter that proved to be the most useful. With every home in Bentonville hooked up to a smart meter that measures hourly electricity and water usage, police looked at the data and noticed Bates used an "excessive amount of water" during the alleged drowning.

Officers have also seized an iPhone 6S, a Macbook Pro, a PlayStation 4 and three tablets in the investigation.

Updated at 11:55 a.m. PT: To add comments from Amazon.