[AlexanderHowl]

Most serial killers rarely kill because they think that murder is fun, it is more that they do it because taking lives are the ultimate exercise of power. To many of them, killing a bioroid would likely be seen as a fairly pathetic exercise of power, much like killing an animal, so they would want proper targets. They would want people, though they might practice on bioroids if they get bored.

As for getting caught, why would the copies care? They would go out in a blaze of suicidal glory rather than get caught, killing as many people as they can before their destruction, because they would know that they would live on as the original and the other copies. I doubt that they would fear destruction because it would only be the end of that instance, as the continued existence of the original would guarantee their immortality. I would not be surprised if they have thermite surrounding their computer cores, so they could literally go out in a blaze of glory, destroying any forensic data.