Who killed Ashfur in Long Shadows?

Hollyleaf killed Ashfur. As you may remember, she was the one out of the three that constantly referred to the warrior code. After she found out that she was the daughter of Leafpool and Crowfeather, she was very frusterated that she was born out of something completely against the warrior code. The code that she had so carefully followed had let her down. So, she killed Ashfur, because Ashfur was going to tell every cat who Hollyleaf and her brother's parents really were.