Turnitin Authorship Investigations

Apparently turnitin has gotten wind of how professors often suspect that a student may have plagiarized a paper or purchased the paper from a third party source.
Since the professors are apprehensive about filing charges due to their sense of having insufficient evidence with which to charge the student, the professor oftentimes just lets the student go scot free.
It seems that Turnitin has developed a solution to that problem through their Authorship Investigation program which is designed to combat "contract cheating" by proving that the student is not the original author of the paper.
While I am still vague as to how Turnitin can accomplish this task, I believe that they just might be on to something here because of the tremendous size of their previously written papers database.
Comparison writing software could be created to help with this investigation aside from their already existing plagiarism software.
While I am not afraid of what the repercussion of this might be for students and writers, since I have evolved from the academic writing business, I am interested to find out if the company can actually pull this off.