Over the years, a good number of studies have been conducted concerning serial rapists, their motivations, their upbringing, their race, their social-economic status, the status of their parents, etc.
Through all of these studies, regardless of their hypothesis, there are at least two trends that have stood out.
First, those rapists with a description that includes the phrase "and it has a hole approximately 45/100ths of an inch in its forehead" have a higher than average probability of being apprehended.
Second, when they are apprehended, those same suspects have a lower than average rate of recidivism.