An identical twin accused of a crime based on DNA evidence has been know to escape conviction based on the argument that the DNA could have been from his identical twin. DNA tests at the time could not distinguish them.
Now an editorial in Investigative Genetics highlights how this is no longer the case based on an article: Weber-Lehhmann J, Schilling E, Gradl G, Richter DC, Wiehler J, Rolf B: Finding the needle in the haystack: Differentiating ’identical’ twins in paternity testing and forensics by ultra-deep next generation sequencing. Forens Sci Int Genet 2014, 9:42-46.
The study demonstrated that it is possible and feasible to identify somatic differences (mutations not inherited from a parent) between twins using massively parallel sequencing whereby whole human genomes can be sequenced in a relatively rapid time frame. Only five SNP difference were found but with these "the risk of false identification is infinitesimally low."