Jerry Buting said he wanted to name Bobby Dassey and Scott Tadych – Avery’s nephew and brother-in-law respectively – as his alternative suspects in the 2007 trial.
He told us the killing of the photographer in 2005 was potentially a “joint-operation”, and to this day believes Avery had nothing to do with it.
Mr Buting told Daily Star Online: “Bobby and Scott, we pointed the finger at both of them.”
The lawyer, who spoke after Avery was granted the right to appeal last month, continued: “I think both, I think it’s likely both, potentially (a joint operation).”
They both deny any involvement in the death, and have never been treated as suspects by police.
Avery is serving life for the tragedy, but Mr Buting argued to jurors he had been framed by Manitowoc County Police.
Mr Buting and co-counsel, Dean Strang, wanted to name Bobby and Tadych as suspects in the trial but this was denied.
They were told they could not provide grounds for motive.
“We had named Bobby Dassey as a suspect in that motion, and the judge said, well yeah he had access and opportunity, he could have done it but you don’t have a motive”
But new lawyer Kathleen Zellner has since alleged evidence of Bobby’s computer containing “images of Ms. Halbach, violent pornography and dead bodies of young females”, as detailed in Season Two of Netflix hit Making a Murderer.
Bobby is also the brother of Brendan Dassey, who was also convicted for the Halbach murder.
But Mr Buting says he and Mr Strang were not aware of the contents on the computer, meaning they could not argue to jurors that Bobby was an alternative suspect.
Mr Buting told us: “We had named Bobby Dassey as a suspect in that motion, and the judge said, well yeah he had access and opportunity, he could have done it but you don’t have a motive.
“Well (what) if we had this information?
“So really they withheld it not just from us but from the court, knowing that the court was going to have to make this determination.
“He was their star witness, saying that he was home and saw her out his window, saw her come up, take pictures and claims he saw her walking towards Steven’s trailer when he then decided to go take a shower, right before he goes hunting, which is weird.
“So we challenged a lot of his story anyway, and also presented evidence that she did what are known as hustle shots.
“He could very easily have flagged her down on her way out and said: ‘hey, I have another car over here, drive around the corner, she was there much time she knew there were other vehicles, and then could have easily have jumped her, overpowered her, taken the car.
“And then we had a witness who saw what appeared to be her SUV driving off the property.
“So he clearly had access and opportunity to have been the killer, but the judge said well you need more than that, you need to show motive.
“That would have, I think, been the link that the judge very well may have allowed it to come in.
“And not only have that allowed us to point the finger at a third party, it would have probably destroyed their star witness, who was as they put it the ‘last person to see her alive’, until other than Steven Avery.”
Zellner fought Avery’s conviction by filing a motion that implicated Bobby and detailed the computer contents.
She argued the evidence had been withheld and not handed over to the defence, according to reports.
She also implicated Scott, arguing he should have been investigated more as a suspect because of “inconsistent statements” and “previous complaints of violence against women”, reports abc2.
This was denied, with the State of Wisconsin arguing they had failed to prove the evidence was suppressed.
Judge Angela Sutkiewicz said: “(Defense attorney Dean) Strang was in possession of Special Agent Fassbender’s report revealing the work of Detective Velie, he acknowledged the detective’s review of the drives when discussing the stipulation proposals, and concluded that the information on the drive in question was irrelevant, a result of a strategic decision on the part of the defense rather than misconduct on the part of the prosecution.”
But Mr Buting said: “The state seized the computer and held it, and had an expert review it, and then they never filed any report about it or even mentioned any of their later discovery until seven months later when Fassbender writes this report that he entitles Brendan Dassey’s computer, and he has one paragraph in there about there being torture porn, and murder porn and that kind of stuff.
“But he makes it sound like Brendan’s searches, not Bobby’s and then, what’s very unusual, he says the report of their expert, which was on a CD, he never booked it in as evidence, he kept it in his own personal possession.
“If he’d booked it in as evidence, we would have seen it, so the delay even when they finally did turn it over, even that summary police report about it, it was like a week or so before our Deny motion, that is our motion to point the finger at a third party suspect was due.”
So why does Mr Buting suspect Tadych, also a witness, as well?
Mr Buting claims nether of their stories stacked up, and says he wanted to argue to the court that Tadych had allegedly tried to sell a weapon at work alleged to be the same model as the murder weapon.
He continued: “They had no alibi, either one of them, either than each other.
“They claimed that they were passing each other, and this is the other weird thing, Bobby had said to the police when they asked him: well what time was it when you guys were driving past each other on the road to go to opposite hunting stands?
“He was like well I don’t really know but Scott would know. Well why would Scott know, why would you think that Scott would know the exact time?”
He added: “With Tadych, this is all in our motion, he had notoriously explosive temper, who later married Barb.
“He had, there is evidence, even in the police interviews, there is evidence he had this explosive temper.”
He continued: “And – importantly – that Scott was hurriedly trying to sell at work the exact same model .22 cal rifle that was claimed to be the murder weapon just after Brendan was arrested.”
Avery was wrongfully convicted of rape and attempted murder in 1985 before he was released in 2003 because DNA proved his innocence.
He was pursuing a lawsuit that could have earned him millions, but he was convicted of Halbach’s murder in 2007.
Manitowoc County Police deny framing Avery for the murder.
Last week, Mr Buting sensationally claimed he feared Avery was going to be killed by police in a framed suicide moments after his conviction.
Daily Star Online has approached Manitowoc County Sheriff’s Office for comment.