Daniel Ellsberg speaks during an interview in Los Angeles on Sept. 23, 2009. (AP Photo / Nick Ut, File)

Daniel Ellsberg, the history-making whistleblower who by leaking the Pentagon Papers revealed longtime government doubts and deceit about the Vietnam War and inspired acts of retaliation by President Richard Nixon that helped lead to his resignation, has died.

Former White House counsel John Dean talks about the Watergate cover-up, that missing 18 and a half minutes of tape, and what the president knew and when he knew it.

Forty years ago, President Richard Nixon resigned his presidency following the Watergate scandal. We talk to Nixon's legal counsel John Dean, described by the FBI as "the master manipulator of the cover-up."