He has footage of the suspected pipe bomber at a Donald Trump rally past year.
"All mail, at all CNN domestic bureaus, is being screened at off-site facilities as of last Wednesday, so this package would NOT have come directly to the CNN Center, even if it hadn't been intercepted first", Zucker said in the memo, according to CNN. A law enforcement official tells CBS News that Sayoc had a list of more than 100 others in his van when he was captured.
The former male stripper, part-time pizza deliveryman and apparent avid Trump fan is charged with five felony counts: interstate transportation and illegal mailing of explosives, threatening a former president, making threatening interstate communications and assaulting federal officers.
The official said authorities had recovered soldering equipment, a printer, and stamps after arresting Sayoc.
The list, which includes names and addresses, was found in the van where he is believed to have lived and constructed the devices. The official wasn't authorized to discuss the investigation and spoke on condition of anonymity.
"There is no imminent danger at CNN Center", he said in a message to employees that was also posted on Twitter.
The FBI said via its Twitter account that the recovered package in Atlanta was "similar in appearance" to the bubble-wrapped manila envelopes authorities say were sent by Sayoc to intended targets from DE to California, including former President Barack Obama, former Secretary of State Hillary Clinton and former Vice-President Joe Biden.
Spokesman Kevin Rowson said via email that the agency had been notified by the U.S. Postal Inspection Service of a suspicious package that arrived at 400 Pryor Street in downtown Atlanta, which is the address of a post office.
PHOTO: In this courtroom sketch, Cesar Sayoc, second from right, appears in federal court, Monday, Oct. 29, 2018, in Miami.
Sayoc is scheduled to appear in court again Friday and will remain in custody at least until then. He faces more than 50 years in prison if convicted on all charges.
Balsamo reported from Washington.
Later on Monday, a manila envelope bearing "some similarities" to last week's packages containing potentially explosive devices was found in an editor's mailbox.
CNN was first to report the additional package Monday, saying the latest mailer addressed to the news organization was discovered at a post office in Atlanta. Sayoc was arrested Friday in Florida after investigators said they identified him through fingerprint and DNA evidence.