Oh that's a good idea! I'm cool with whatever you decide to make Anna do.

There's two ways I can see this going.

1. Anna and Lucio hides the body themselves. This burden weighs down on Anna, eventually leaning on Lucio for comfort, since they both share a secret together. They had slain a vampire together. He saved her life. 

2. She finds her father, (werewolf) Helps the deal with the body, and your RP how you want the family to respond. If she tells her father, he could reveal their family secret to her or something.

I'm TOTALLY just throwing some ideas to you. Maybe to help you brainstorm. 

I don't want you to think these are the only two options or me telling you what to do. :)