jus·ti·fied, jus·ti·fy·ing, jus·ti·fies
v.tr.
1. To demonstrate or prove to be just, right, or valid: justified each budgetary expense as necessary; anger that is justified by the circumstances.
Adj. 1. homicidal - characteristic of or capable of or having a tendency toward killing another human being ; "a homicidal rage"; "murderous thugs"
Rage (emotion), an extreme, energized usually explosive state of anger
okay,.... So based on the definitions found in a google search,... there can be a person motivated by valid circumstance who feels driven to kill human beings in an extreme manner.