Carla Chase was making the long drive to Waupun Correctional Institute to visit with her uncle, Steven Avery, when she heard the news her cousin Brendan Dassey's conviction for the 2006 murder of Teresa Halbach had been overturned by a federal judge.

She tells PEOPLE she didn't believe the decision could be real at first, but quickly went on Google and saw multiple news reports.

"I was 15 to 20 minutes away from the prison when I found out, and I was pretty much in shock," Chase tells PEOPLE exclusive. "I thought, 'Nah...this can't be.' But I went online and double checked and it was everywhere. It was a rush and a shock, all at the time same."

Both Dassey and Avery were the subjects for the hit Netflix true crime documentary series, Making a Murderer. In March 2006, Dassey, then 16, told investigators he had helped his uncle rape and murder photographer Teresa Halbach on Oct. 31, 2005. He later recanted, claiming his confession had been coerced.

Dassey's confession to law enforcement is perhaps the most debated aspect of the Netflix series.

Judge William Duffin's decision holds that the authorities promised Dassey, who is described by many in the series as having learning disabilities, prosecutorial leniency in exchange for his cooperation during his March 1, 2006, interrogation.

"The investigators repeatedly claimed to already know what happened on Oct. 31 and assured Dassey that he had nothing to worry about," the decision reads. "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 Fourteenth Amendments."

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The judge's decision suggests he had "significant doubts" concerning the reliability of Dassey's confession.

"Crucial details evolved through repeated leading and suggestive questioning and generally stopped changing only after the investigators, in some manner, indicated to Dassey that he finally gave the answer they were looking for," the ruling reads. "Purportedly corroborative details could have been the product of contamination from other sources, including the investigators' own statements and questioning, or simply logical guesses, rather than actual knowledge of the crime."

If Wisconsin's Attorney General fails to appeal Friday's ruling within the next 90 days, Dassey will be freed from prison. A spokeswoman for the attorney general's office declined to comment on Dassey's case on Monday.

Chase tells PEOPLE her phone hasn't stopped ringing since Friday night. She says Dassey's family has been refusing all media interview requests since last week's development.

Over the weekend, filming for Making a Murderer's second season began in Manitowac, Wisconsin, Chase says.

"Now, we're just playing the waiting game and hoping no one files an appeal," Chase explains. "I know his mother has talked with Brendan on the phone, but he hasn't called any of the other family. He's overjoyed."

Prison staff allegedly gave Dassey two hours to clear out his prison cell.

"When your conviction is cleared, they move you from one area of the prison to a different area of the prison," Chase says. "The family is very hopeful he'll be released. But like I said, he could get out in two weeks or it could be 90 days. The prosecution needs to have actual evidence to move forward with his re-trial, but they don't have any new evidence."

Steven Avery's Attorney Optimistic

On Friday, Making a Murderer's directors and executive producers Laura Ricciardi and Moira Demos issued a statement to PEOPLE saying, "Today there was a major development for the subjects in our story and this recent news shows the criminal justice system at work. As we have done for the past 10 years, we will continue to document the story as it unfolds, and follow it wherever it may lead."

Kathleen Zellner, Avery's new attorney, tells PEOPLE, "We are thrilled for Brendan Dassey that his conviction has been overturned," adding, "We fully expected this outcome from an unbiased court that carefully examined his confession."

According to Zellner, she was just visiting with Avery, who "is so happy for Brendan. We know when an unbiased court reviews all of the new evidence we have, Steven will have his conviction overturned as well."

On the day of Dassey's confession, lead investigators Tom Fassbender and Mark Wiegert pulled him out of school and questioned him alone for hours.

During that questioning, Dassey told investigators he had helped Avery kill Halbach, saying that they shot her in the head and burned her body at a bonfire on the Avery property later that evening.

Calumet County Prosecutor Ken Kratz called a press conference shortly after investigators secured the confession, saying that Dassey described in detail Halbach's brutal assault and slaying.

However, after seeing portions of the confession on Netflix, many came to believe he was coerced by Fassbender and Wiegert, who repeatedly question him until the teen gives them a confession.

In a recorded exchange with his mother, Barb Janda, following the confession, Dassey says, "They got in my head." The teen later denied that he ever saw Halbach and said he had nothing to do with her murder.

It has not been announced when the second season of the Netflix show will air.