What is anthrax? how was anthrax used in the crimes?

Anthrax is a rare bacterial disease spread by animals, insects, and mosquitoes. Victims may feel ill or have skin ulcers and difficulty breathing. I believe that you can find how it was used in a (story I believe in your case) by trying to find its significance of it to the story. Try to imagine what the story would be like without it? Does it change the ending? 

Hope this helps!

The answer is hilum.