JB . I’ll give you an example. Many years ago, a lady (Rachel Nickel) was snatched and stabbed on Wimbledon Common.
A man was found shortly after her murder, called Colin Staggluft was found London wandering around armed with huge blades. He looked exactly like the photo fit, he had no alibi, several witnesses picked out of a line-up.
They couldn’t find a single scrap of DNA from the crime scene which matched Stagg.
The police felt sure they had their man so they strengthened their case by sending out a ‘honey pot’ policewoman who offered sexual favours in return for information on how he killed Rachel.
The judge halted Stagg’s trial because of this as it was illegal, the case was thrown out. Stagg spent years taking abuse and being told that he was evil, a murderer, shouldn’t be free, threat of violence against his family.
A few years later a man killed 2 more women and a child. A DNA match was found to be food. They were also tipped off by a local. Robert Napper, it’s accepted that Robert also murdered Rachel too.
After years of threats and abuse, Stagg was totally innocent.
These thing do happen. You might think the story of a man going out poaching whilst in the same park close by his doppelgänger committing a horrendous murder.
This why we have trials.