In June 2009, Israeli forensic science researchers published a ground breaking study that put credence to the possibility of creating artificial Deoxyribonucleic Acid (DNA) that can fool current forensic testing procedures. The researchers asserted that anyone with the proper equipment and basic understanding of molecular biology could create artificial DNA in virtually unending amounts. Furthermore, the research demonstrates that the current American forensic science system utilized by law enforcement is incapable of distinguishing between artificial and genuine DNA.
It's here: the law of evidence on Spindle Law. See also this post and this post.