Both... but neither, for the serial killer finishes the good doctor (part of the 11) and is himself put to death after being caught (capital punishment). Serial killers usually target the scum of society, or those indulging in immoral or unethical/illegal behavior, therefore the doctor was involved in unethical/illegal behavior. He serves a higher purpose, ie vigilante.
The research scientist, though he makes a break through, benefits no one but the ultra wealthy as his patent is cubby holed and only for sale for those that have lots of money - it does not benefit the masses.
Another factor is the mode of transportation. The serial killer would definately be associated with this form of public transportation as he scouts out a victim, ie prostitute, etc. The doctor, however, is also engaged in something illegal or unethical as this mode of transportation is not likely given grants and or research money. The good doctor would more than likely own personal transportation of some kind and therefore would not be taking public transportation for commutes or city to city travel (would take a plane).