Homicidal nurses share common traits
Yes, that's a real headline, taken from the Oct/Nov 2003 issue of "European Hospital", reporting on a paper by Prof. Karl H. Beine, published in the International Journal of Law and Psychiatry 26/2003.
Apparently, most homicidal nurses are male (just like most serious criminals then, so that's not a particularly useful conclusion), and they "use crude language." An indicator that "something is going terribly wrong" is that the offender "[often] correctly predicts the exact time of death of patients."
And finally, I'll leave you with Prof Beine's amazing deduction that "sympathy for the patients [was not] a trigger for the carer to murder them."