A US federal judge has overturned the murder conviction of Brendan Dassey, whose case was examined in Netflix's popular Making a Murderer documentary.
Following the ruling by the judge in Milwaukee, Wisconsin, Dassey, 26, will be released within 90 days, unless the state decides to retry him.
Dassey and his uncle Steven Avery were convicted of murdering young woman Teresa Hallbach in 2005.
Avery and Dassey, who was 16 at the time, were sentenced to life in prison.
On Friday, Judge William Duffin stated in the court ruling that investigators in the 2007 trial made false promises to Dassey by assuring him "he had nothing to worry about", the Associated Press news agency reported.
"These repeated false promises, when considered in conjunction with all relevant factors, most especially Dassey's age, intellectual deficits, and the absence of a supportive adult, rendered Dassey's confession involuntary under the Fifth and 14th Amendments," the judge said.
The verdict comes after Dassey's appeal was rejected by state courts.
The case received wide attention in the US and across the world after the release of the 10-part documentary Making a Murderer in December 2015.
The filmmakers cast doubt on the legal process to convict Dassey and Avery.
The documentary tells the real-life story of Avery, who was wrongfully imprisoned for 18 years for sexual assault.
After his release he was then accused and found guilty of murdering Teresa Halbach.
The series focused on the conduct of law officials in Manitowoc County, Wisconsin, who risked a huge financial penalty over the first case.