Making a Murderer twist: Filmmakers say prisoner confessed to murder of Teresa Halbach

Steven Avery in Making a Murderer: Part One. Photo / Supplied

Filmmakers for the Making a Murderer spinoff Convicting a Murderer have said an unnamed prisoner has admitted to the murder of Teresa Halbach in a taped interview.

The confession could clear the names of Steven Avery, 57, and his nephew Brendan Dassey, 29, the subjects of Netflix's Making a Murderer.

The pair have spent almost ten years behind bars in relation to Halbach's death, despite both maintaining their innocence.

Filmmakers have reportedly handed over the recording to police - but the director Shawn Rech told Newsweek he cannot confirm the legitimacy of the investigation.

However, the filmmaking team says they have collected an "unfathomable amount of information and evidence."

Rech says: "Our investigation does not end here."

According to reports from The Sun, Dassey's case has already gone to the Supreme Court, but the request for a new trial has been denied, and Avery's case is still in the appeals process.

Netflix's documentary series Making a Murderer shone a spotlight on the trials of Avery and Dassey when it was released on the streaming platform in 2015, and alleged there were issues with the legal processes that convicted the pair of Halbach's death.

Teresa Halbach disappeared in 2005 following a visit to the Avery family salvage yard in Twin Rivers.