Australia's most notorious serial killer could have been caught before he murdered seven backpackers, had the 'wrong man' not been sent to prison, a new investigation has claimed. Channel Seven's Sunday Night will tell the story of Ivan Milat's first violent crime and how he escaped police prosecution, before going on to butcher seven backpackers. The revelation includes first-hand evidence from Milat's older brother, Boris, into the killer's 'secret victim'. Scroll down for video . A new report claims Ivan Milat, Australia's most notorious serial killer, could have been caught before he murdered seven backpackers . Boris Milat shares a secret he has kept for 52 years, which details how Australia's bloodiest butcher was responsible for the shooting more than two decades before the first backpacker murder in 1989, according to the report. The program also puts Mr Milat face-to-face with the 'wrong man', who was jailed for the first crime his brother committed. 'Don't hold yourself responsible,' the man, who Channel Seven has not yet named, tells Mr Milat, as they shake hands. According to the timeline presented by the program and Mr Milat, his murderous brother would have been a 19-year-old when he claimed his first victim. Former Detective Paul Gordon tells the program the evidence uncovered is 'unbelievable' and 'incredible'. Boris Milat tells the program a secret about his brother he had kept for more than 52 years . Milat was later sentenced to life in prison, but if the 'wrong man' (right) had not been jailed for his first crime, Milat's victims could have been saved, the program claims . 'Don't hold yourself responsible,' the man imprisoned for Milat's first violent crime told the killer's brother, Boris . Milat, 70, was convicted of butchering seven young people between 1989 and 1992 and burying their bodies in the Belanglo State Forest in southern NSW. He has been locked up in Goulburn's Supermax jail for almost 20 years. The first two bodies of Milat’s victims were discovered on September 19 and 20 1992, when two runners found a decaying corpse in the Belanglo State Forest. According to claims made by the program, Milat would have been about 19 when he claimed his first victim . The daughter of Milat's first victim (left) is told her father was shot by the serial killer. Former Detective Paul Gordon (right) tells the program the evidence uncovered is 'unbelievable' and 'incredible' The report claims Milat's seven victims could have been saved if he had been been held accountable for this first chilling crime . Police later confirmed the bodies were of missing British backpackers Caroline Clarke and Joanne Walters. Walters had been stabbed 35 times and Clarke had been shot 10 times in the head. The grim finds were just the beginning of a long and extensive search which resulted in the bodies of Australians Deborah Everist and James Gibson being found in October 1993, followed by Simone Schmidl’s stabbed body in November of the same year. The decapitated body of German backpacker Anja Habschied was then found along with her boyfriend Gabor Neugebauer on 3 November 1993 in shallow graves 50 metres apart. British backpacker Caroline Clarke had been shot 10 times in the head when police found her body . First victims: Australians James Gibson and Deborah Everist, both aged 19, were Ivan Milat's first known victims after they disappeared in December 1989 and their bodies were found in the Belanglo State forest almost four years later . Simone Schmidl's body was found in November 1993. She had been stabbed to death . Milat was convicted of the seven backpacker murders on July 27, 1996 and for the attempted murder, false imprisonment and robbery of Paul Onions. He kept the shirts, sleeping bags, a water bottle, portable stove and backpacks of his victims hidden in roof and wall cavities, in what was described as an 'Aladdin's Cave', in the house he was arrested in 20 years ago. Boyfriend and girlfriend German backpackers Gabor Neugebauer and Anja Habschied were found dead on 3 November 1993 in shallow graves 50 metres apart . British backpacker Joanne Walters, is another one of the victims of backpacker murderer Ivan Milat . Sinister souvenir: In this photograph police seized from the house of Ivan Milat's brother William, the serial killer is seen carrying the sleeping bag which belonged to Deborah Everist who with boyfriend Jame Gibson was the first of Milat's victims killed in the Belanglo State Forest . The evil killer has penned a series of rambling letters while behind bars, according to a book released by his eldest nephew, Alistair Shipsey. The Milat Letters, is a compilation of 94 notes from Milat to his eldest nephew Alistair Shipsey. Milat is serving seven consecutive life sentences for the murders of seven backpackers in  NSW between 1989 and 1992. In the letters, he tells Shipsey about his 'fair share' of 'sheilas', who write 'some frightening things' - and one woman who has even proposed. Australia's worst serial killer Ivan Milat kept trophies to remind him of each murder . Milat butchered and buried the bodies of seven young people between 1989 and 1992 in the Belanglo State Forest in southern NSW . 'Every month someone new writes; the latest one was from Texas. She tells me she’s 25, white. I ought to ask her “why” as she only knows me from a website, and there’s nothing nice about me on it,' one of the letters reads. 'As you know there are a lot of wackos out there as well. A lot of them write to me at times. I tell you Al, there are some real crazy people out and about.' Milat has been a troublesome inmate during his time in prison, and it is believed he planned at least one escape and swallowed metal objects in an attempt to get out of jail. An extract from one of the letters from Milat, written before he chopped his own finger off with a plastic knife in January 2009, affectionately refers to Shipsey as 'Al . In prison, Milat, has been a troublesome inmate, having planned at least one escape, swallowing metal objects and cutting off his own finger to send to the High Court in an envelope . One of his letters revealed plans to cut off his own finger and mail it law enforcement. ‘I will send them parts of my hand first, I have been considering this for a while and only need half a reason to show them how I feel with their sh**head ideas, there is not much they can do to me any more and at my age I don't give a f**k,' an excerpt from his letters reads. Milat tried to send his finger it in a padded envelope to the High Court. The full story,The Ivan Milat Secret, will air on Channel 7 at 8:30pm on Sunday.
Report claims Ivan Milat shot first victim years before backpacker murders .
The 'wrong man' jailed for attack, which left Milat free to kill, report says .
Milat's brother, Boris, says he has kept the shocking secret for 52 years .
Milat brutally murdered seven backpackers between 1989 and 1992 .
He is serving seven consecutive life sentences at Goulburn Supermax jail .