What happened to the forvalaka which killed Tom-Tom?

This is the dialogue between Croaker and One-Eye and the end of chapter one.

“This isn’t the one that killed Tom-Tom. It doesn’t have the scars we put on it.” I turned slowly, studied the legate. He laughed again, looking our way. One-Eye never figured it out. And I never told him. We have troubles enough.

What didn't One-Eye understand?

I've read the first two books - The Black Company and Shadows Linger.