STOCKTON- Is the FBI investigating Mayor Michael Tubbs and his assistant, Daniel Lopez? Derek Bluford, a self-proclaimed former “confidential human source” for the FBI and author of “The Mighty Have Fallen: The Inside Story of the FBI’s Investigation into Political Corruption” (available on Amazon: https://www.amazon.com/Mighty-Have-Fallen-Investigation-Corruption/dp/1734763736) is alleging Mayor Michael Tubbs and his assistant, Daniel Lopez, whom worked previously for former Sacramento Mayor …