"This incident is extremely disturbing and does not represent the values of the Los Angeles Police Department," Chief Michel Moore said.
"There was NO evidence to support a storyline" that Kathy Scruggs traded sex for tips about Richard Jewell, his attorney tweeted. "We never made such a false & damning claim."
Burke enacted a dramatic shakeup of NBCUni leadership in January that placed Shell in a prime position to replace him, insiders said at the time.
Negotiations had recently resumed with the militant group in a bid aimed at ending America's longest war.
A judge has extended a temporary restraining order until Jan. 2 in the case on whether a hospital can take baby Tinslee Lewis off life support.