You might be playing at a level that is a too hard for your character. Also, be sure to ask for others with a motive before you ask other questions - even alibi. This will build your suspect list for you. And as soon as you can, buy new skills that will help prevent clamming. You are tough, so you can focus on Interrogation (for suspects) and Intimidation (for townspeople.) Don't bother with the charming skills. Also, toughness gear you win through favors or purchase will help you. Subscribing and joining an agency will help as well. Plus, it's more fun!