Steven Avery's lawyer has raised a number of points questioning the evidence used to convict her client of the murder of Teresa Halbach.
Kathleen Zellner suggests it does not make sense that the real killer would go to the trouble of trying to destroy her body yet be sloppy enough to leave traces of his involvement elsewhere.
Avery, now 53, was convicted of Halbach's murder in 2007 and sentenced to life imprisonment without parole.
His story has been told in the phenomenally successful 'Making a Murderer' documentary.
During a search of the property on which Steven Avery lived, Manitowoc Police discovered Halbach's remains inside a burn pit and numerous pieces of evidence linking him to the crime.
Since the documentary was aired internet sleuths have poked holes at the case against him, with some asking how and why the bones were also found at a quarry miles away from Avery's home.
During the trial, forensic anthropologist Leslie Eisenberg testified saying she "suspected" a couple of bone fragments from the quarry site "appeared to be" from a human pelvis.
She added: "There was human bone as well as nonhuman bone in that barrel."
Zellner (left) and Avery (right)
Theories have suggested evidence such as the blood found in Halbach's car was planted after a tube containing Avery's blood appeared to have been tampered with and its seal broken.
None of the defence theories were enough to persuade jurors of his innocence at his trial in 2005, but Zellner hopes to launch an appeal in the hope for another go.
The lawyer says not enough was done to investigate the death of Halbach and recently opened up about her work in an interview with TheLipTv.
She said: "There was a very poor investigation done of the victim's background, who she was involved with and circumstances of her life.
"It had all the hallmarks of a wrongful conviction case and then when I met him I realised in the time I spent with him in 15 or 20 hours, I absolutely don't believe he committed this murder.
"I don't believe he is capable of committing a murder. But that's not the key thing - it's the evidence that's just flawed."
