The fiancée of Making a Murderer's Steven Avery has revealed for the first time that she broke off their engagement after he failed to adopt her Christian faith - but is continuing in her fight to prove his innocence.

Sandra Greenman, 73, told Daily Mail Online that very few people visit Avery in prison and that his brothers, Charles and Earl, have never gone to see him in the nine years since he was convicted of Teresa Halbach's murder.

At one stage he said they may have committed the murder.

Avery, 53, was sentenced to life without parole for killing the 25-year-old photographer in 2005. Her last known whereabouts was at the Avery family salvage yard, where she had gone to photograph a minivan for Auto Trader magazine.

When Avery was arrested for Miss Halbach's murder, he had been free for little more than two years after being exonerated in September 2003 on DNA evidence following 18 years in prison for a rape he did not commit.

Former couple: Sandy Greenman and Steve Avery in a picture she keeps at her home of the two in her back yard. In fact the two have never met outside of prison but she had the image created to show them as they would be

Hope: The appointment of a new lawyer - Kathleen Zellner, a high-profile Chicago attorney with a long list of post-conviction victories under her belt, begging her to take Avery's case - has sparked renewed belief in the possibility of Steve being freed

Victim: Teresa Halbach, 25, was murdered after she went missing in Manitowoc County in October 2006, having last been seen by Steven Avery. Whether he murdered her is at the heart of the Netflix series

At the time of his arrest, Avery was suing Manitowoc County for $36 million over wrongful imprisonment.

Avery's nephew Brendan Dassey, then 16, was also found guilty of Miss Halbach's murder and sexual assault, and sentenced to life with the possibility of early release in 2048.

Both men claim that they are innocent.

Their story is the subject of a ten-episode series, released last month, which has captivated viewers around the world.

As Avery's relatives, case investigators and witnesses come under fresh scrutiny, Mrs Greenman, who goes by Sandy, revealed exclusively to Daily Mail Online that she had halted her plans to marry him.

She said: 'Steve and I were engaged to be married and I broke it off. It's not that I've ever stopped trying to work for him but it was a religious thing. I cannot marry someone that's not a Christian.

'Since we broke off the engagement, I've visited him less and less. It's too hard for me. I still love him and want the best for him. I want him out.

'He calls any time he can and he says I'm being stubborn. But we will see what happens. It's a friendship right now.

'I don't know how it's going to end and if he gets out, it's a whole different story.'

Sandy added: 'But it doesn't change anything. I will always be behind him and he's my best friend.'

The retired lab researcher has been a tireless supporter of Avery following his murder conviction.

Sandy said: 'I went [to visit him] in all kinds of weather, in fog and on slippery roads.

'I've tried so hard to help him be different in his feelings. I know he prays but it's just not the same. I know that he would feel better if he had something to believe in and something to hold him tight.'

She added: 'He's building up resentment towards all these people who did this to him.'

Avery is allowed to have up to 12 visitors in prison, according to Sandy, but there are far fewer on his list – usually just herself, and his parents, Dolores and Allan Avery.

He also manages to make a couple of phone calls each week – usually to Sandy and his mother, 78.

Few visitors: Sandy Greenman tells Daily Mail Online that she, Steven's mother Dolores (above) and father Allan are the only visitors he usually has

Estranged: Steve Avery's brother Charles (left) and Earl have not been to see him in nine years, since his conviction for the murder of Teresa Halbach

Distance: Earl Avery has also not seen his brother since his conviction. In legal papers in 2009 Steven Avery suggested that Charles and Earl could have been the real killers, although their mother has dismissed the theory

Two years ago, Avery was transferred from a maximum-security prison in Boscobel, four hours' drive from his family in Manitowoc County, to Waupun Correctional Institute, which is only 90 miles away.

Sandy said: 'His cousin Kim [Ducat, who appeared in Making a Murder] has gone once to see him and they get along very well.

'When he was in Boscobel, his daughter Jenny came a couple of times but other than that, his kids don't come. They don't know him, they didn't grow up with him.

'His sister Barbara has been once to take his parents. His brothers have never visited. As far as I know, there isn't anyone else.'

In 2009 court papers, Avery, who had just been sentenced to life without parole, claimed that his two brothers, Charles and Earl Avery may have murdered Miss Halbach. The legal documents were originally obtained by TMZ.

However when their mother, Dolores Avery, was asked about Steven's 2009 filing and the potential involvement of her other sons by Daily Mail Online, she sprang to the defense of all three.

She said that Steven may have been extremely desperate about being sent back to die in prison after he was freed in 2003.

Dolores said: 'He wrote that [legal document] when he was prison, maybe he felt he had to do something. But it wasn't anything to do with them [Earl and Charles Avery].'

Sandy believes that Avery's arrest for murder and the subsequent confession of his 16-year-old nephew Brendan, his sister Barbara Tadych's son, divided the family.

'It's a shame, it split the family apart,' Sandy said. 'A lot of it was [because of] the Dassey confession which the prosecution used against Steve. There was a lot of bad blood there for a long time.

However Sandy said that most of the family appeared to have slowly healed the rifts.

'I'm not involved but I think things are much better now,' she said. 'I think the relationship between Barbara and her parents seems terrific now. They realized that it wasn't Brendan talking and he was just trying to say something to satisfy the interrogators.'

Sandy first contacted Steven Avery with a letter of support after watching his 2007 murder trial.

She told Daily Mail Online that she would rush home from her job as a phlebotomist testing blood at a local hospital to watch the six-week televised trial with her husband, Wallace.

Real culprit: Gregory Allen committed the crime for which Steven Avery was wrongfully convicted and spent 18 years in prison: The 1985 sexual assault of Penny Beernsten

Eligible for parole: Gregory Allen could be allowed out as early as this year for the offense he is jailed for, the 1995 sexual assault of a woman in Green Bay

Overlap: Allen and Avery almost met in prison. Sandy said: 'Allen's in New Lisbon [prison]. He had been in Waupan and I knew he couldn't be there anymore because they wouldn't put Steve in the same place.'

Sandy, who had never met Avery or any of his family, believed he was innocent from the beginning.

She said: 'My husband Wally also [believed he was innocent]. I can't tell you why, we did not know the man, had never met him. It was just a feeling.

'I worked early mornings at the hospital and the trial started around 9am. I couldn't wait to get home to watch it.

'Both my husband and I felt the same - this man was telling the truth. He just did not do this.

'He [Avery] had been in prison for 18 years for something he didn't do. He lost his family because of that - he had five kids including a stepson.

'Then he got out of prison and he was in line to get millions of dollars from his lawsuit.

'His life was back on track, he was engaged to get married. Why would he do something like that [Teresa Halbach murder]?

'And after I met the man, I knew there was no way it could be true.'

Sandy first went to meet Avery at her husband's suggestion. Wallace Greenman was suffering from Parkinson's disease and dementia and his health was too poor to make the 340-mile round trip from their home in Neenah to the Wisconsin Secure program facility in Boscobel.

Sandy said: 'It was my husband who urged me to go see him [Avery]. Wally was ill with Parkinson's. He went down there once but it was a major mistake. It's a three-and-a-half hour drive and he wasn't able to do that.

'Wally told me I should write to Steve which I did and I wrote to the judge too about his case.'

Sandy recalled feeling jittery on the long drive to meet the convicted murderer for the first time.

She told Daily Mail Online: 'When I first went down to see Steve, I had never been in a prison in my life.

'I was scared to death on that ride to Boscobel, I didn't know what to do. I was thinking, what do I say to this man? I don't know him.

'When they brought him in, I told him who I was because he had never seen me before. I said, 'Hi, I'm Sandy and I know all about prison because I've watched [movies] The Shawshank Redemption and The Green Mile. So not a problem.' That got him laughing.

'We had three hours of solid conversation. It was like I had known him for 100 years. We found that we liked a lot of the same things and the time went really fast, so I went back.

'He turned out to be my best friend.'

Despite being convinced of Avery's innocence while watching the trial, not long after meeting him in person, Sandy asked him directly if he had committed the heinous murder.

She said: 'I looked right at him and I said, 'Steven, I don't think you're guilty or had anything to do with this but it's perfectly alright for you to tell me if you did.'

'I really wanted to know. I told him, 'I'll still come to see you, it won't stop that. I just want to know if you had anything to do with the murder or if you were involved in any way.'

'I tried to think of all the scenarios – maybe he wanted to date her [Miss Halbach] and she rebuffed him. Maybe all kinds of things.

'Steven looked right at me and he said, 'Absolutely not, I did not kill her. I promise you I didn't.'

Sandy continued: 'From that moment on, I knew that he didn't [have anything to do with the murder].

'I can't believe anyone could look at you like that and after I gave him the perfect opportunity to tell me.

'I have started a prison ministry so it doesn't matter guilty or innocent, I still want to talk to people.

Hope for the future: Sandy Greenman says she believes in Steven Avery's innocence and hopes that she will see him achieve his freedom

Visitor: Sandy Greenman says

'But he looked at me and said: "She came and took pictures of the car, she had done it before. She's never been in my trailer, she came to the door to get money and left. I didn't do it."

'I've never asked him again. Because I knew that he did not kill her.'

Sandy later discovered during her visits that Avery cannot stand the sight of blood.

She said: 'And he was accused of doing all that stuff? I don't think so.'

In fact, it was the evidence of Avery's blood found in Miss Halbach's car which Sandy has questioned the most.

The DNA evidence was integral to the prosecution's case to prove Avery's guilt.

Defense lawyers, Dean Strang and Jerry Buting, claimed at trial that Avery's blood had been planted in the car.

In December 2006, weeks before the trial was due to begin, Buting had unearthed a decade-old vial of Avery's blood at the Manitowoc County Clerk of Court's office.

The vial was found inside a Styrofoam box with a broken seal in an area easily accessed by a number of people. The rubber stopper on the vial also appeared to have been injected with a needle.

The prosecution's response was to test the blood for EDTA – a chemical used to preserve blood.

According to reports, EDTA testing had only been used once before by the FBI – at O.J. Simpson's murder trial in 1995 – and was considered by many experts to be unreliable.

However, Judge Patrick Willis ruled that the prosecution would be allowed to use the results from the EDTA testing before the jury.

Testing on Avery's blood from Miss Halbach's car found no EDTA was present– which the prosecution claimed was conclusive evidence that it had not come from the vial and therefore was not planted.

Sandy told Daily Mail Online: 'The thing that bothers me the most is that tube of blood. It was discovered in an evidence room and had definitely been tampered with. And no one came forward to say, "Oh, I did that."

'EDTA is so fickle. I know from my work in the lab, you can take a large amount of blood in which you know that EDTA is present and you won't find it. And you can take a smaller amount and you might find it. It's there sometimes and sometimes it's not.

'The way I understand it was the EDTA test was figured out on the Avery case. I wrote to Judge [Patrick] Willis that the test was extremely unreliable and they should not do it but they did.

Also convicted: Brendan Dasse. Steven Avery's nephew Brendan Dassey (left, when he was convicted, and right, receiving his high-school diploma in prison)

'During the trial, I would see these things and I'd just go crazy.'

Another key piece of evidence against Steven Avery was Teresa Halbach's car key which was found on his bedroom floor.

The key was discovered on the seventh search of Avery's trailer by Lieutenant James Lenk, of Manitowoc County Sheriff's Department, without another officer present.

Three weeks earlier, Lt. Lenk had been deposed in Avery's civil lawsuit over alleged wrongdoing in his rape trial.

Manitowoc County Sheriff Jerry Pagel had also stated that the investigation of Avery's property in the search for Teresa Halbach would be handed over to neighboring Calumet County to quash any suggestion of misconduct.

Despite Manitowoc deputies supposedly taking a supporting role in the investigation, most of the physical evidence was found by them.

It is unclear how the key, found in plain sight next to a pair of slippers, was missed on six prior searches of the small room.

According to the court testimony of Manitowoc Sheriff's deputy Andrew Colborn, he had shaken a bookcase and the key fell out. Colborn was also previously deposed during Avery's civil lawsuit over alleged misconduct.

The key had Avery's DNA but not his fingerprints. Miss Halbach's DNA was not found on the key.

Sandy said: 'It was the seventh search - and keys which drop out of from behind a cabinet would have dropped straight down.

'But that key flew – right by the slippers where there would be [Avery's] DNA. Perfect.

'There was no DNA on the key except Steven's DNA. If [Teresa Halbach] had touched the key at all, her DNA would be there. It wasn't which means it was wiped clean.'

Sandy added: 'That's another thing we noticed during the trial that just didn't make any sense.'

She and her husband were aghast when the jury returned a guilty verdict to Avery after deliberating for three days.

'We were just amazed when [the jury] said guilty,' she said. 'I remember we were both sitting there and watching that verdict on TV. Steve just shook his head.

'Wally and I both said together, 'you have got to be kidding me' because of reasonable doubt. It was a mess from the start.'

Sandy said some of her close friends struggle to understand her resolute belief in Avery's innocence.

'One friend asked me, 'Why did you get involved with that particular person? There's been other people who have been falsely accused of things.'

'I don't know why my husband and I felt so strongly about the Avery case but we did.

'[After the trial] I put money on the phone for Steve to call and my husband talked to him too.'

Wallace Greenman passed away seven years ago after suffering a heart attack at the age of 88.

A year later, Steven Avery asked Sandy to marry him after they realized their feelings had developed beyond a friendship.

Current prison: Waupun Correctional Institution, where Steven Avery is now incarcerated. 'They tried to get him to take a class called something like "How to react to your life when you're released". 'He said: "I've got a life sentence plus ten years, why would I want to take that?',' Susan Greenman tells Daily Mail Online

Previously held: Avery spent time at the Wisconsin's maximum-security facility in Boscobel, four hours' drive from his family in Manitowoc County

Sandy said: 'I believe the Lord wanted me there and I believe I was right in what I was doing.

'Steve was so good to me and helped me through my husband's illness. I told him everything and you would not believe the encouraging things he said.

'It was very much mutual support. He got me through my husband's sudden death.

'Wally passed away in April 2008 and a year later, Steve asked me to marry him.'

However Sandy had concerns about becoming the wife of a man who had been sentenced to die in prison.

'I thought we could have married but prison is just not a place for that. There have been people Steven knows [who have had a prison marriage] – but it has ended in divorce every time, mainly because it's very hard to maintain a prison relationship.'

Although Sandy believes that Avery has been wrongly convicted, the 73-year-old grandmother says she is heartbroken for Teresa Halbach's family.

She told Daily Mail Online: 'I feel terrible for the Halbach family.

'At one motion hearing for Steven, I remember seeing Mrs Halbach. I knew I couldn't but I wanted to say to her so badly, "I feel so bad for you because I don't know how horrible it would be to lose a child, especially that awful way, but are you sure you got the right man?"

'"With all the doubt in your heart do you know or is the real one out there running around maybe killing another daughter?"'

"I feel so bad for you because I don't know how horrible it would be to lose a child, especially that awful way, but are you sure you got the right man?"With all the doubt in your heart do you know or is the real one out there running around maybe killing another daughter? What Steven Avery's fiancee wanted to say to Teresa Halbach's mother

Sandy believes that Avery would bear no ill will to the Halbach family just as he did not place any blame on Penny Beerntsen, the rape victim whose testimony helped wrongly convict him in 1985. However she said second time around, Avery might find it harder to forgive.

Sandy said: 'When Steve first got out and Mrs Beerntsen asked him, 'Can you forgive me?' he hugged her and said it was perfectly fine. He held no animosity towards this woman who had put him away.

'He said when he got out, he had no ill will towards any of them. All his anger just melted away.

'But he has said to me, 'I don't know if it's going to happen this time.'

She added: 'He's getting bitter, that's the word I'd use. I told him outright, 'I think you're becoming bitter - you don't trust lawyers and you don't trust other people.'

Avery spends all his time in prison trying to prove his innocence and works each day on his case.

Sandy told Daily Mail Online: 'He spends all of his time on the case and it has been that way for years.

'In Boscobel he had a job as it gave him something to do, even for a few hours. One job was outside, supervising the rec. He loved that job but you are only allowed to keep a position for two years before it's changed over.

'Before they moved him [to Waupun], he was setting up the dining area.

'When he got to Waupun, he didn't want to do anything. They tried to get him to take a class called something like "How to react to your life when you're released".

'He said: "I've got a life sentence plus ten years, why would I want to take that?"

Avery, who has an IQ of 70, scours for legal loopholes in his case using the prison's law library after the failure of his Supreme Court appeal meant he was left without a lawyer.

Last year, Avery petitioned the circuit court without an attorney but the motions were denied in November.

Sandy said: 'When Steve realized he was without a lawyer, he tried to do this on his own but was getting denied left and right.

'When it comes to legal stuff, I don't think his IQ is very low. He's worked it all out from the law library and studied books which show how to file legal documents.'

Steven used to keep some boxes of his case's transcripts in his cell but they were returned to the basement at his parents' home.

Sandy said: 'He would go through the boxes again and when he was done, he would send them home.

'He does not want to die in prison. Although if something's not done, I'm afraid he will.'

Avery's last few court-appointed attorneys have been little help, Sandy said.

She was encouraged by the last lawyer who took on Avery's case, saying he had a 'gung-ho attitude' of getting to the bottom of it. Then he suddenly withdrew.

Another attorney bluntly told them that taking on Avery's case would be bad for his practice.

Visitor: Jenny Avery is one of the only one of Steven's children to have visited him behind bars

Sandy told Daily Mail Online: 'It was all handled so badly, it's just so sad. What he needs is another look at this trial to give him a second chance.'

After a decade fighting for Avery's cause, Sandy is under no illusions.

She told Daily Mail Online: 'What happens if he gets another trial and he's found guilty again? Well, I guess we have to give up then.

'I know that you can run out of appeals and he's almost there. But give him a chance at another trial with a better lawyer.'

Avery requested to watch Making a Murderer but was denied the privilege by prison authorities.

However he has seen newspaper clippings about the show, brought to him by his former defense attorneys, Dean Strang and Jerry Buting.

Sandy said the renewed attention has been mostly positive and given him hope.

She said: 'He's been getting a lot of letters, I don't believe he's had any bad letters. He's received gifts too – sweatpants and some other things. The gifts are coming from all over the world.'

The filmmakers, Laura Ricciardi and Moira Demos, were never allowed to visit Avery in prison in the ten years it took to make the documentary.

Avery only appears on screen in archive footage and can be heard on recorded telephone calls from prison.

Making a Murderer captures Sandy's first contact visit with her boyfriend after she spent several years visiting him behind glass at Boscobel.

She told Daily Mail Online that shortly before they met face-to-face, she had an argument with him over the phone.

Sandy said: 'So on my way to Waupun, I didn't know if I wanted to kick him or kiss him. But when I came out of the prison I was so emotional, I was crying. I asked them to turn the camera off.'

Sandy doesn't subscribe to Netflix but has watched the entire series on DVDs given to her by the filmmakers. Much of it has been difficult viewing.

She told Daily Mail Online: 'There were tears through a lot of that documentary. It bothered me a lot of it. It's a sad situation.'

The documentary left her horrified at the handling of Brendan Dassey's case which she had previously known little about.

'Poor Brendan, I am just in shock. I have no idea what they put him away on. The only thing they had was a false confession. 'He had no idea what was going. First of all, he was only 16 and secondly, he's very slow. Sandi Greenman on Brendan Dassey

In March 2006, four months after Miss Halbach's remains were found on the Averys' land, Dassey told authorities that he helped his uncle rape, stab, shoot and dismember the victim.

Dassey, who is classified as having learning difficulties, confessed to sexually assaulting Halbach and cutting her throat on his uncle's orders. He later said the confession was coerced.

The teen was found guilty of Miss Halbach's murder and sexual assault in August 2007. He was sentenced to life in prison with the possibility of early release in 2048.

Sandy said: 'Poor Brendan, I am just in shock. I have no idea what they put him away on. The only thing they had was a false confession.

'He had no idea what was going. First of all, he was only 16 and secondly, he's very slow. He was in special education. But I give him a lot of credit, he has gotten his high school diploma in prison.

'But it is so sad because they had nothing – no DNA, no fingerprints, nothing on this kid.'

She added: 'A lot of what bothered me was watching Len Kachinsky [Dassey's one-time defense attorney] and Michael O'Kelly [an investigator drafted in to help elicit a confession].

'I knew this had happened from the transcripts but then to see it on film. Kachinsky always had a silly grin on his face as if to say, I got this covered, I know what I'm doing.

'They should not have been on the case. To try to get Brendan to take a plea deal and say he was guilty when the poor kid doesn't even know what he's talking about he's so mixed up.'

A lawsuit for Dassey has been taken to federal court in Wisconsin by Northwestern University's Center on Wrongful Convictions of Youth.

The suit claims that Dassey was illegally imprisoned in 2005 and asks that Dassey be granted a writ of Habeas corpus, meaning his case must be re-examined.

A decision is likely to be made in the next year.

Sandy said: 'I do believe Brendan will get a new trial and maybe this documentary will help. If anyone needed a new trial, it's Brendan.

New hope: Kathleen Zellner (right) the Chicago lawyer who is now to look into Steven Avery's case. She has achieved a series of appeals, including the acquittal of Mario Cascario (center) last September, who had been convicted of the 2002 killing of a store co-worker

Original lawyers: Dean Strang and Jerry Buting remain close to Avery

'The lawyer being like he was, he definitely needs another chance.

'The years might have made a difference in his thought process. Maybe he realizes now what they were doing to him.

She added: 'I always ask Barbara how Brendan's doing and she says pretty well under the circumstances.

'But Brendan still always asks when he can come home.'

Sandy praised the documentary-makers and said they had striven to tell Avery's story accurately.

'They didn't make him out to be this wonderful person who couldn't possibly have done this. He is human and they showed what he did,' she said.

'They tried to get the other side involved and asked Ken Kratz [special prosecutor in the Steven Avery murder trial] but he had certain stipulations. But they wanted him on there.'

Sandy added: 'Kratz made a big deal about stuff being left out – well you can't get everything in ten hours.

'There's stuff I wished was in there. There's stuff left out on both sides. '

Sandy said although Making a Murderer had stirred strong emotions, there was no excuse for the vile messages being sent to certain people featured in the series.

Manitowoc County Sheriff's Department has received death threats, according to news reports. Special Prosecutor Ken Kratz and Dassey's former defense lawyer, Len Kachinsky, have also received threats.

'In a way it's terrible because what has happened has given Wisconsin and Manitowoc County a bad name,' Sandy said.

'But I do not approve of what some people are doing with threats. It's making the Avery supporters look like fools. Don't threaten anyone - including Mr Kratz.'

Despite a warning from the filmmakers that there would be a lot of public interest when the series was released, Sandy said she was still shocked by the amount of attention.

She told Daily Mail Online: 'Overall, the attention is good but I didn't expect the firestorm for me.

'I've had messages from all over, there are so many people contacting me from so many different places. The majority of messages are positive.

'In one Facebook comment someone wrote about the Halbach family and said how terrible it was to bring this all back to them.

'And I agree – I put something on social media about the Halbach family and how badly I felt for them. I know this has to be hard to have it all back.

She added: 'But it still comes down to two men sitting in prison for life – two men that need to be out if they didn't do it.

'Let's get the right one. If it's Steven so be it – then he belongs there. But I just don't think it is.'

'Let's say that there's no relationship or friendship with Steve, or anything else with the Avery family - even if I didn't know him, like it was in the beginning. No matter what happens in the end with Steve and me, I want him out, I want him to have a life. No matter who it's with or where it is. If he's innocent, and I truly believe he is - you can put that down a thousand times - I believe in his innocence or I would not be in this Sandra Greenman

Sandy noted that following Steven Avery's wrongful conviction for rape in 1985, the real perpetrator, Gregory Allen, was left free to attack other women.

Allen was sentenced to 60 years for sexually assaulting a woman in Green Bay, Wisconsin, in 1995. He is eligible for parole in October 2016, according to the State of Wisconsin's Offender Database.

In a twist of fate, Allen and Avery almost crossed paths at the same prison.

Sandy said: 'Allen's in New Lisbon [prison]. He had been in Waupan and I knew he couldn't be there anymore because they wouldn't put Steve in the same place.'

She believes that Avery and Dassey's only shots at justice are with new trials and has worked relentlessly for years to find a lawyer who would take on Avery's case.

'I've emailed hundreds of lawyers and made close to 100 phone calls.

'I've gone to lawyers' offices in all states and been turned down every single time. I've been told by around 15 of them that they will take the case - for $100,000.

'There was a lawyer from Florida who was very interested but said he couldn't do it for less than $100,000. I said well, I have to say goodbye.'

Four years ago, Sandy contacted Kathleen Zellner, a high-profile Chicago attorney with a long list of post-conviction victories under her belt, begging her to take Avery's case.

Sandy said: 'I kept emailing and I wrote, 'It's me again, I'm sorry, I'm stalking you but I feel so strongly - you're the one that's going to get him out.'

'Initially, she could not take the case because she was too busy. But she kept Steve's files and said some day she might be able to look at it again.'

Ms Zellner announced on Friday she would be taking on 'full and complete' representation of the Avery case with assistance from the Midwest Innocence Project.

Sandy believes that new evidence or witness information could see Avery granted a new trial.

'She said: 'It's been ten years, there is a lot more sophisticated testing now. But where is that [vial of Avery's blood] now? Somewhere in an evidence room I imagine.

'Is it even possible to test it anymore? I don't know. If EDTA shows up at all [in blood matched to Steven found in Halback's car], then that shows beyond a shadow of a doubt that he was set up.

'If he was set up, he deserves a new trial.'

Regardless of her personal connection with Steven Avery, Sandy's ultimate goal is to see justice done.

She said: 'Let's say that there's no relationship or friendship with Steve, or anything else with the Avery family - even if I didn't know him, like it was in the beginning.

'No matter what happens in the end with Steve and me, I want him out, I want him to have a life. No matter who it's with or where it is.

'If he's innocent, and I truly believe he is - you can put that down a thousand times - I believe in his innocence or I would not be in this.

'I wouldn't have fought so hard to get him a lawyer if I thought he had any part in this whatsoever.

'I would have been his friend but I wouldn't have fought to get him out – because he didn't belong out [if he did this].

'I pray so hard that justice will be done even if that means they find him guilty again. If something new comes up that really looks like he really committed murder, I'll be very shocked - but so be it.