Steven Avery, the subject of the insanely popular Netflix docu-series Making a Murder recently spoke out to his supporters through a letter saying he’s willing to take "every forensic test possible." Now it’s his sons who are speaking up about the controversial murder convictions and whether or not they think he’s innocent, PEOPLE reports.

Avery was exonerated after serving 18 years for a wrongful rape conviction only to be back behind bars for the 2005 murder of 25-year-old photographer Teresa Halbach. He maintains his innocence and one of his sons wholeheartedly agrees.

"No, I don’t think he did,” Bill Avery said in an interview with Crime Watch Daily when asked if he thought his father committed the crime.

Twin brother, Steven Jr., isn’t so sure. "I have no idea," he said. "I mean, only one person can answer that and that is Teresa. But she can’t answer it no more."

With their father behind bars for most of their lives, many are wondering what their relationship must be like. "I just see him as a complete stranger. I know that he’s my father, but I grew up without a father for so long that it just kind of feels like I don’t have [one]," Bill said.

The full interview airs Feb. 8.