Well, assuming you can afford competent representation... It would be next to impossible to link any particular case of injury to any particular action on your part, so you would quite likely avoid arrest forever and probably be acquitted if it came to trial. You would technically expose yourself to a massive amount of civil liability, but if you could make the argument that many other people are going around doing the same thing, you would wind up paying for a very small share of the damage that you caused. Outside of specific laws passed to punish your specific behavior, you probably get off more or less scott free.
Of course, it has never been difficult to terrorize people like this, and what you're imagining is small potatoes. Just build a big building which does this on a daily basis for decades. We call it "pollution", and mostly shrug it off as the cost of progress.
Eh, I appreciate the link, but I don't really see the connection. Aside from the common theme of radiation exposure, what you posted involves a medical technician performing unnecessary procedures on people. This makes it easy to demonstrate a) that the exposure occurred, b) that the tech knew the effect of the machine and that the procedure was unwarranted, and subsequently c)that his intention in doing this was to harm the victims, or something similarly sinister. It wasn't part of that appeal, but there's also the issue that he did this by taking x-ray images of women's bodies, and I'd imagine a large part of the conviction came from we really don't want a weirdo in the hospital getting off on x-raying female patients.
Never mind that it was a court-martial, and that he was convicted of multiple counts of drug use and dereliction of duty at the same time.
All in all, it has very little in common with our hypothetical, in which one invisibly, untraceably exposes members of the public at large to some unknown dose of ionizing radiation over a period of time. And you've really done nothing to address my observation that, in reality, people get away with that all the time in the form of environmental contamination. We can prove he ate the fish, we can prove he died of cancer, we can prove you're putting cancer in the water. That's just not enough to convict you for his death-- the worst you'll face is a stiff fine under a law that exists only to impose a stiff fine if you put cancer in the water and somebody dies.
Of course, it has never been difficult to terrorize people like this, and what you're imagining is small potatoes. Just build a big building which does this on a daily basis for decades. We call it "pollution", and mostly shrug it off as the cost of progress.