She used the unforgivable curse Avada Kadavra which is the killing curse.
because shes bellatrix lestrange and she works for voldemort and is evil.
Sirius Black was murdered by his cousin, Bellatrix Lestrange, because she is the crazy, murderous type. He wasn't on Voldemort's side and Bellatrix was one of Voldemort's loyal servants.
Voldemort did kill James and Lily Potter, but it was Bellatrix who killed Sirius Black.
well most people would say Sirius because he is not a death eater and he does not want Harry to die... but I personally say Bellatrix sirius is really nice and he's a favorite character of mine but.... i think bellatrix is pretty awesome.
Bellatrix Lestrange was the one who killed Sirius Black in the battle of the Death Eater's and the Order of the Phoenix in the Ministry of Magic.
Orion Black is Sirius and Regulus Black's father. They are both first cousins of Bellatrix Lestrange.
Sirius. Bellatrix kills him.
Sirius Black (Harry Potter's Godfather) was murdered by bellatrix lestrange, Sirius's Oldest Cousin.
Bellatrix is very pro pure-bloods and Sirius who is against that was not seen as a cousin to her but as someone on the other side who she would be happy to kill - in fact because he was related to her she wanted the 'pleasure' of killing him herself.
Bellatrix Lestrange was Nymphadora Tonks' aunt. But Tonks' father was muggle-born so the Black family disowned Tonks' mother, Andromeda. Bellatrix hated that her neice made the line unpure and during a battle killed her.
Bellatrix Lestrange
Sirius Black. His cousin Bellatrix Lestrange killed him