'Murderer' in the Bible

Now Elisha [was] sitting in his house and the elders [were] sitting with him, and [the king] dispatched a man from before him, but before the messenger came to him, he said to the elders, "Did you see that this son of a murderer has sent to remove my head? Look, when the messenger comes, close the door; and you must {hold the door closed against him}. [Is] not the sound of the feet of his master behind him?"

Now Jehu had come in the gate, so she said, "[Is it] peace, O Zimri, murderer of his master?"