Amazon has refused to hand over data from an Echo smart speaker to US police, who want to access it as part of an investigation into a murder in Arkansas, according to court records seen by tech industry news site The Information.

Arkansas police issued a warrant to Amazon to turn over recordings and other information associated with the device owned by James Andrew Bates. Bates has been charged with the murder of a man found dead in his hot tub in November 2015.

The Seattle-based tech company twice declined to provide the police with the information they requested from the device, although it did provide Bates’s account information and purchase history, the report said court records show.

Although the Echo is known for having “always-on” microphones to enable its voice-controlled features, the vast majority of the recordings it makes are not saved for longer than the few seconds it takes to determine if a pre-set “wake word” (usually “Alexa”) has been said. Only if that wake word has been heard does the device’s full complement of microphones come on and begin transmitting audio to Amazon.

While that would seem to limit the use of the Echo data in the investigation, the device is also occasionally accidentally activated, through similar sounds. Those snippets of audio could potentially be useful to police investigating a crime, as could the timing information of when they were recorded. According to the report, the court records show police took the Echo and extracted some data from it.

US prosecutors and defence attorneys have both found new uses for “smart” device data in the courtroom in recent years, especially information collected by wristwatch-style Fitbit activity trackers. In 2014, a Canadian woman sued her former employer over a debilitating injury she claimed to have sustained during her work as a personal trainer; she submitted data from her Fitbit to prove that “her activity levels are still lower than the baseline for someone of her age and profession,” according to reports.

Conversely, when a Florida woman claimed an intruder had assaulted her, police used information from a Fitbit she had been wearing during the alleged assault that suggested she had in fact been asleep at time. She was subsequently charged with filing a false report.

Amazon’s reluctance to part with user information fits a familiar pattern. Tech companies often see law enforcement requests for data as invasive and damaging to an industry that considers privacy a prime selling point. Last year, Apple went to court with the FBI over the bureau’s demand that that company break its own encryption on an iPhone belonging to one of the shooters in the San Bernardino spree killing.

But firms often retain a “back door” for their own use – to automatically scan emails for key terms used to target advertising, for example – and that can complicate claims that law enforcement access would uniquely invade a user’s privacy. Amazon’s internal approach to user data will likely prove integral to its ability to resist the warrant.

In the Echo case, police also extracted data from a different smart home device, a water meter. Bates’ smart water meter recorded a flow of 140 gallons between 1am and 3am, the report said. Prosecutors claim this is an unfeasibly large amount of water use, and allege it was the result of the garden hose being used to spray the patio clean of blood. Bates’s defence team disputes the accuracy of the readings.

Bates pleaded not guilty in April 2016 and is on bail awaiting trial early next year.