A NEW image has been released of a woman police believe may hold the key to tracking down the killer of Robert Hart at the Parklife festival.
Robert, 26, died on Wednesday June 11, five days after the assault at the music festival which left him fighting for life with a bleed on the brain.
Last week's Crimewatch appeal featured pictures of 12 possible witnesses who officers believed could hold information crucial to the investigation.
As a result of that programme and subsequent assistance from the media, GMP have been able to identify eight of the 12 people pictured, but are still keen to speak to the other four who are yet to be identified.
Of those four, officers are particularly keen to speak to one woman in particular, who was pictured wearing a dark, check flat cap and purple sunglasses.
DCI Phil Reade said: "Our trained officers have examined a huge amount of pictures and video footage sent in by festival goers and have determined that this woman may well be of assistance to our investigation.
"The time at which she was photographed, the area she was stood, the direction she was facing and the fact she seems to taking a video or pictures of the area where Robert was standing all suggest that she may well have captured a picture of the man responsible or the people he was with.
"Obviously, obtaining evidence such as that would represent a big step forward in this investigation and take us closer to catching the man responsible for this attack.
"I would urge her, or indeed any of the other three people pictured, to come forward and speak to us as soon as possible.
"One thing we have learned from speaking to the other eight witnesses is that any small piece of information could potentially prove useful to Police.
"One of those witnesses did not come forward initially as they believed that they would not be able to provide anything new to the investigation, which was simply not the case.
"Their witness statements provided new details that were previously unknown to officers, which proves that no piece of information is too small and that it is vital for witnesses to come forward should they think they know anything at all about the attack."
Robert Hart's girlfriend, Gemma Parry added: "Despite the best efforts of GMP officers, Rob's family and myself to persuade him to do so, it is becoming less and less likely that the man responsible for his death is going to come forward of his own accord.
"That makes these potential witnesses all the more important, as they may well hold the key for Police to track down the man who took Rob away from me, from his mother, brother, sisters, nieces and nephews.
"I am now speaking to the woman pictured in the flat cap, or any of the other witnesses officers want to speak to, please contact Police.
"Imagine if it was your husband, your boyfriend, your brother or son, try to imagine our suffering, knowing that the man that stole our beautiful Rob away from us may never be brought to justice.
"You can make a difference.
"You might be able to help provide us with the closure we so desperately need, that Rob so desperately deserves. Please."
Anyone with information can contact the incident room direct on 0161 85 69283 or email the incident room on firstname.lastname@example.org with any relevant footage.
Alternatively you can call police on 101 or independent charity Crimestoppers on 0800 555 111.