John Markoff:

Carnegie Mellon University research scientist, joined Google in 2009 to help create the then-secret effort. He took over leadership of the team after Sebastian Thrun, the Stanford computer scientist and founder of Google X laboratory, left in 2013.
 Johnny Luu, a spokesman for Alphabet, the parent company of X, the company’s research division that oversees the car project, confirmed Mr. Urmson was planning to leave.