What is a grand jury, who serves on it and what is it used for? A criminal law expert tells you everything you need to know.
Presidents past have used this nearly limitless power to halt criminal prosecutions before. What's to stop Trump?
Hoover abused his power as FBI director to serve presidents' interests. The reforms that followed were set up to prevent it from happening again.
How will Mueller perform as special counsel? A historian compares his actions with another former FBI director to find out.
The investigation is likely to end in one of two ways: the end of Donald Trump’s presidency, or the beginning of his second term.
An FBI historian tells stories from the agency's ups and downs over 109 years and four dismissed directors.