That study... Yeah, it's bad science, or bad journalism, depending on whether it's the researcher or the reporter who made the leap from "people say you have autism" to "you actually have autism".
What they did was look at news articles about serial killers and mass murderers. Then they checked to see which ones the press had speculated about having ASD traits. About a quarter had had a newspaper reporter make that assumption about them. Only one, Adam Lanza, had a pre-existing ASD diagnosis.
So, the only conclusion you can draw is, "journalists like to say that mass murderers and serial killers have autism."
In reality, autistic people can become murderers, but we are not more likely to become murderers than NTs are. If you take the whole population of people with autism, and check to see who commits crimes, there's no increased crime rate among autistics.
Here's such a study:
Pervasive developmental disorders and criminal behaviour: a case control study.
The prevalence and pattern of criminal behaviour in a population of 313 former child psychiatric in-patients with pervasive developmental disorders were studied. The patients were divided into three subgroups and compared with 933 matched controls from the general population. Age at follow-up was between 25 years and 59 years. An account of convictions in the nationwide Danish Register of Criminality was used as a measure of criminal behaviour. Among 113 cases with childhood autism, .9% had been convicted. In atypical autism (n=86) and Asperger's syndrome (n=114) the percentages were 8.1% and 18.4%, respectively. The corresponding rate of convictions in the comparison groups was 18.9%, 14.7%, and 19.6% respectively. Particular attention is given to arson in Asperger's syndrome (p= .0009).
So Aspies are more likely to play with fire, but for every other crime, we're either much less likely (classic autism) or no more likely (AS) to commit a crime.
The serial-killer study does not connect autism with murder. It connects murder with retroactive speculation that you may have been autistic--and that says much more about how people talk about crime, than about how autistic people actually behave.
To my fellow autistics:
Don't let this affect your behavior. Let them talk. Let them call you killers, if they want. You are still the same compassionate, caring people you always have been. You do not have to become vengeful or turn prejudice back against NTs, just because they claim that's what you want to do. Once you have set them straight and they still call you a killer, there is nothing you can do about the way they talk. The best revenge is to be the person you know you should be. When you help rather than hurting others, you don't need to have people praise you for it, or even notice it. Let them call you killers--you will know you are not; you will know the world is a little better because you are in it.