My former employer is under a multi-agency federal investigation. I've been asked to speak with a couple of fed agents and a DOJ attorney. If I can't set something up with them I was told I'd be subpoenaed. I have no idea what the scope of the investigation is or what my involvement is. Should I have an attorney present during my interview with them? I know I didn't knowingly do anything wrong but I want to be careful since I have no idea what types of questions will be asked of me.