From The Grey House:
Judith was a Slayer and the angels had told her where to find Natalia. The angels didn’t speak to Dean. He wasn’t a Slayer and didn’t know if he would ever be a Slayer. Judith turned to Dean fully and withdrew a pistol from her jacket.
“You made me miss. The vampire whore will live.”
He tried not to visibly relax. Dean didn’t want Natalia dead. He liked her and wanted to save her instead of killing her. Then he saw the gun. “Judith, you can try again another time.”
“There won’t be another time. The angels are warning me; my time is almost at an end. The whore needed to die today.”