Justice Department: 'Zip it' on Ayers probe

"The Obama Justice Department instructed San Francisco police officials not to comment after top law enforcement officers there signed a letter accusing Weathermen radical Bill Ayers and his wife, Bernardine Dohrn, of being directly behind the 1970 bombing of San Francisco's police station that killed one sergeant and wounded nine others."

Now the San Francisco Chronicle is reporting the police group members who signed the letter received calls from the Justice Department and a local police chief telling them to remain silent.