Presley commented / asked:
Raises the question, is it useful to consider "lone wolf" assassins a class of criminal apart? Do we entertain such categorical notions when considering other kinds of criminals, even narrowed down to just murderers?
With murders and sex crimes notably we do - in the UK - and have borrowed the adjective from the FBI IIRC of 'serial murderers' etc. It is a fact that some criminal suspects specialise in their targeting, such as bogus callers on the elderly. There is a clear difficulty in defining and establishing predictability and the political need, notably with terrorism, to pre-empt such behaviour.