Isidoros Zourgos in his novel "Στην σκιά της πεταλούδας" mentions that if you kill a wolf, the animal's spirit will come back and kill you after forty days.
The origin of the belief is assumed to be Adrianoupoli (Edirne), in Turkey (the "old country" of the novel). It may be a Greek belief, as the characters of the novel are Greek and Adrianoupoli at the time of novel (1910s, early 1920s) had a significant Greek population.
The belief isn't mentioned in Wikipedia's Wolves in folklore, religion and mythology and I didn't find anything about it around the net. Wikipedia does mention a similar Cherokee legend, but I don't think it's likely that is the one Zourgos is referencing. The belief is mentioned in connection to an illiterate Greek refugee from Andrianoupoli in the late 1910s. Not someone I'd expect to be well-versed in Cherokee folklore.
I wonder if this is an actual folklore belief of the area, or something the author made up.