You answered the following questions and created a character for the investigation:
Who are you?
What drives your character?
What unique knowledge/talents/skills do you have?
Who do you know?
What material resources do you have?
How do you know each other?
Why would someone come to you for assistance?
What do you, the character, want to get out of this investigation?
What do you, the player, want to get out of this game?