Brendan Dassey of ‘Making a Murderer’ wins appeals court ruling

A federal appeals court has upheld a ruling that overturned the murder conviction of Brendan Dassey, who was featured in the Netflix series “Making a Murderer.”

The ruling marks a major victory for Dassey, now 27, whose confession became a key subplot in the series.

Dassey was convicted in 2007 in the slaying of Wisconsin photographer Teresa Halbach. In 2005, Dassey, then 16, confessed to authorities that he assisted his uncle, Steven Avery, in raping and killing Halbach. Her charred remains were found on Avery family property in Manitowoc County.

The 10-part Netflix series, which premiered in late 2015, renewed interest in Avery’s ongoing legal troubles, leading to calls for his release and a petition seeking a presidential pardon.

Court documents stated that Dassey IQ’s was “assessed as being in the low average to borderline range.” Dassey later recanted.

US Magistrate Judge William Duffin overturned Dassey’s conviction in August, citing his age, intellectual deficit and lack of guardian during questioning. Duffin called the confession “so clearly involuntary in a constitutional sense that the court of appeals’ decision to the contrary was an unreasonable application of clearly established federal law.”

The state appealed the ruling, sending the case to the federal appeals court and blocking Dassey’s release.

On Thursday, the Seventh Circuit Court of Appeals voted 2-1 in favor of upholding Duffin’s ruling.

“A few factors and passages from Dassey’s confession support the majority’s view that the confession was not voluntary. Many other factors and passages support the state courts’ view that overall, the confession was voluntary. The Wisconsin Court of Appeals could have been much more thorough in its discussion, but its conclusion was within the bounds of reason, the ruling said.

The state of Wisconsin has 90 days to retry Dassey or the decision becomes final.

The attorney general’s office did not immediately return a request for CNN comment. The Journal Sentinel in Milwaukee received a comment from the Wisconsin Department of Justice, which said it was evaluating the decision.

“We anticipate seeking review by the entire 7th Circuit or the United States Supreme Court and hope that today’s erroneous decision will be reversed,” said spokesman Johnny Koremenos. “We continue to send our condolences to the Halbach family as they have to suffer through another attempt by Mr. Dassey to relitigate his guilty verdict and sentence.”

Avery, 54, is serving a life sentence at a Wisconsin prison. He maintained his innocence throughout his original trial. He said he was framed and is seeking a new trial.

CNN’s Eliott C. McLaughlin contributed to this report.