There was zero evidence left at the scene, because paramedics tried to save Jill's life and destroyed any hint that was left. Same for Barry George's coat, the lack of traces is because they got ahold of the coat over a year later, during which time any traces disintegrate so to speak.
The particle in the coat's pocket is pretty damning evidence, but was at the retrial deemed inadmissible (due to a suggestion only!) and that's what led to the "not guilty" verdict, which isn't an "innocent" verdict at all. Just means that the presented evidence and narrative aren't conclusive for a "guilty" verdict at the time. Juries can also be fickle.
They had the right guy, the crime and criminal's profile fit the crime to a T (loner, misogynist, sexually violent towards women, stalker, focussed on female celebrities; broke into KP grounds apparently trying to abduct/rape Diana) and he was let go.
Nick Ross's article is a fantastic read and it doesn't need to be read in its entirety to understand why and how it was BG. No one can say it aloud though, as it's against the law and BG has sued left, right and centre. Was him though, no doubt about it.
Criminologists have from the start made clear it was a "loner stalker type", from day one, Nick Ross made it from day one clear as well (at the time he did 15 years of Crimewatch and has a psych degree). The "criminal underground" "connections" were all followed and all lead to nothing, as there was nothing to be found.
At the end the criminal is exactly who it so often is for women: Women are usually killed by men, who have known them, "crimes of passion" as they are called at times. BG was also around Jill's house earlier that day, suggesting he was regularly walking by/ stalking the house. It didn't need info from outside that Jill would be there, when BG lived up the street and spent his days stalking women and walking aimlessly around. In the first month about four calls came in pointing towards BG. But because he used a number of aliases it wasn't instantly clear that the same man was meant. His ex-wife said he is capable of murder, she fled back home to Japan after a year of marriage. BG assaulted and stalked women and was convicted and known to police.
I honestly don't understand how anyone can doubt it was anyone but BG, esp after the linked article above.
Netflix didn't do a good docu, they didn't ask a number of relevant questions and as one review put it very well: they basically do a wiki page in video; no conclusion, no questions, nothing. Not entirely pointless, but not that well done, either.
Mansfield will rot in hell though, can't believe that someone can defend a criminal with such a straight face and point towards "evidence" that simply doesn't make sense and has quickly been checked and dismissed.