Telegraph.In experiments, a team of Israeli scientists were able to obliterate all traces of DNA from a blood sample and add someone else's genetic material in its place.
The process was so successful that it fooled forensic scientists who carry out DNA fingerprinting for American courts.
The findings threaten to undermine the key forensic technique, which has secured thousands of convictions in Britain and around the world.
It demonstrates that, in theory, criminals could plant samples of blood or saliva at crime scenes to cover their tracks while leading to innocent people being wrongly convicted.
Dr Dan Frumkin, who led the research, said: If you can fake blood, saliva or any other tissue, you can engineer a crime scene.
You have full control of the situation. Any biology undergraduate could perform this.
So what now? DNA has become so heavily relied and trusted upon, the fact that it can be manipulated and faked seems to render it useless as an absolute guarantee of proof.