Amazon's Echo Alexa could help solve a murder

amazon echo device alexa murder
Police want to know what Alexa has to say about their murder investigation (Reuters)

Alexa is always listening, but could she hold clues to the murder of a US man found dead in a hot tub?

Authorities think so, but Amazon - which makes the Echo smart home device that answers to the name 'Alexa' - won't hand over the data.

In what's believed to be a legal first, police in Arkansas sought to have data from murder-accused James Bates' device handed over to help their investigation, the Washington Post reports.

Police were called to the Bentonville home in November 2015 to find Victor Collins' body face up in a hot tub with serious injuries to his face.

Mr Bates, who was the one to call police, told officers he and some work colleagues, including Mr Collins, had stayed up the night before drinking and watching football.

He said he let two of them stay at his place and then went to bed. He woke up shortly afterward and claimed to have then come across Mr Collins' body.

But the clues told police something else had happened that night - broken knobs and bottles, and blood spots around the hot tub pointed to a struggle.

Several days later, the Arkansas chief medical examiner ruled the death a homicide prompting a police investigation.

They found a number of smart home devices including an alarm system, a wireless weather monitoring device, a thermometer and an Amazon Echo.

Investigators seized the Echo and serve a warrant to Amazon stating they had "reason to believe that Amazon.com is in possession of records to a homicide investigation".

Amazon has refused to comply with the order.

The case has raised issues about such devices which are always on and 'listening'.

The Echo, which has seven microphones, responds when the user says a 'wake word' which, in most cases, is "Alexa". It then begins streaming audio to the cloud.

Police don't specify what exact data they're looking for or expect to find on Bates' Echo or what it could have captured that night.

But the device would have only been recording if someone had said the 'wake word'.

Bates has pleaded not guilty to first-degree murder and is on bail awaiting his trial next year, the Washington Post reports.

His lawyer Kimberley Weber told technology industry news outlet The Information she was shocked by the police's request.

"You have an expectation of privacy in your home, and I have a big problem that law enforcement can use the technology that advances our quality of life against us," she said.

Police were able to find other information to help their case, including from smart meter data from the Bentonville utilities department.

It showed 530 litres of water was used between 1am and 3am on the night of Mr Collins' death - an amount of water well above normal use at the property since 2013.

Earlier that night, the four never used more than 37 litres of water an hour.

Police say the water used between 1am and 3am was "consistent with spraying down the back patio area, which may have resulted in the wet concrete patterns observed on the morning of November 22".

Newshub.