AN AMAZON Echo could become the star "witness" in a double-murder case as cops believe the device has captured audio of the knife massacre.

Timothy Verrill, 34, allegedly stabbed Christine Sullivan, 48, and Jenna Pellegrini, 32, to death in the US town of Farmington, New Hampshire in January 2017.

Verrill was charged with first-degree murder and pleaded not guilty.

But prosecutors believe the Echo device may have captured audio of one of the killings.

A judge ruled on Friday for Amazon to hand over any recordings taken by the Echo device from “the period of January 27, 2017 to January 29, 2017”.

The Amazon Echo device was seized by police during the investigation, according to court documents.

The potential recordings are now stored on an Amazon server.

It is unclear if any audio of the crime was recorded, but the court found probable cause that the speaker could have captured critical evidence.

In particular cops hope it could have recorded evidence of “crimes committed against Ms. Sullivan, including the attack and possible removal of the body from the kitchen”.

Sullivan was stabbed eight times and had her skull fractured and Pellegrini was stabbed 43 times, according to authorities.

The bodies were dumped behind the house under a tarp and a knife was found nearby, police said.

Prosecutors believe the audio evidence could make their case stronger.

Police testified in August 2017 that Verrill knew Sullivan’s boyfriend who she lived with, and had access to home’s security code.

Manchester ABC affiliate WMUR also reported Verrill was seen on the home’s CCTV with both women before they died.

An Amazon spokesperson said it would not release the recordings “without a valid and binding legal demand properly served on us”.