If successful, you'll influence laws and society for decades. You'll probably influence some people for their entire lives, if you can possibly be horrible enough to stain them emotionally. If you are a really decent rapist, then your genetic influence will probably last quite a while, especially if you rape in states that don't like abortions, even in cases of rape by mass murderers. If you can murder or rape selectively, such as selecting people who match some phenotype or genotype, then your genetic influence would be much, much greater.
yeah, but what is remembered is more a reflection of those remembering than it is of those remembered. In other words, it's a sign of how the world is now that we think back farthest on our murdering/raping ancestors and our more evolved future generations may reflect back on things like massive economic advances brought via something uniquely ours so far throughout history, technology. The times they are a changin!