Looking for a specific fictionbook about horoscope murders.

I read a book in the early 2000s about a series of murders at a high school. Each murder was targeted at a specific star sign. Taurus was killed by a double bladed knife making it look like he was gored. Aquarius was drowned. I think Scorpio was poisoned. Please help me find it. It is hard to search for because of the Zodiac killer.

by Rahknathal