English translation: the perpretators, those in charge
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Explanation: I seem to understand that in your text the word is used in the first two instances with its meaning of offenders, culprits, those responsible for (see above suggestions), whereas in the latter two examples you provide it seems to mean "those in charge" (of the office or whatever) or the like
this was the most comprehensive answer as to the the different meanings of "los responsables" in English.
I found "the perpretators" a very good option for the original request, but you cannot please everyone 4 KudoZ points were awarded for this answer