Verkkosnape's source was almost certainly more reliable because he had told voldemort (at least) that it came from within the order.
Snape was prepared for.
Verkkoby the end of this article, you will not only answer the question about snape's fate but also gain a deeper understanding of his significance in the harry.
Verkkoinstead, snape delivered himself to voldemort after the dark lord's duel with harry potter in the graveyard and claimed that he had not left the school.