NEW YORK (AP) — Even before it was opened, the oversized letter sent from Cho Seung-Hui to NBC News attracted attention. The postal worker who brought it to NBC’s Manhattan headquarters on Wednesday pointed out the return address of Blacksburg, Va.

Inside was what NBC anchor Brian Williams described as a multi-media manifesto, with video, pictures and writing from the murderer of 32 people just before he went on his killing spree at Virginia Tech. Cho mailed it at 9:01 a.m. Monday, between murders.

It was mass murder for the YouTube generation, a chilling document from a man who said little in life but clearly wanted people to know his grievances in death. And it started a frantic day for a news organization that, for the second time in a week, suddenly found itself at the center of the nation’s biggest news story.

The package was addressed to 30 Rockefeller Ave., mistaking the Plaza for a street. Incorrect zip codes were written twice and crossed out — the failure to settle on the right one delaying the letter’s arrival by a day.

NBC security opened the envelope, a policy they have taken with suspicious packages ever since anthrax was delivered to anchor Tom Brokaw shortly after the September 2001 terrorist attacks. They handled it with gloved hands, and quickly made copies of what they found.

At noon, NBC News President Steve Capus was called out of a news meeting by security chief Brian Patton and told what had been delivered.

“At first I wondered if it was real, but when you look at it and see all the pictures you realize that it is,” he said.

The package contained a DVD and a 23-page printout of a computer file that mixed rambling, profane messages with 29 pictures of the killer. Eleven photos showed him aiming a gun at the camera.

One photograph showed 30 hollow-point bullets, with the message written underneath: “All the s--- you gave me right back at you with hollow points.”

“I recoiled in horror,” Capus said. “It was chilling.”

Through NBC’s Justice Department correspondent, Pete Williams, NBC reached out to authorities. A representative of the FBI’s New York office came to NBC to get the originals, and NBC was asked not to say anything about it publicly until investigators could examine it, a request Capus thought was appropriate. The first public word of what NBC had wasn’t released until a news conference in Blacksburg around 4:30 p.m. EDT.

“If we wanted to do something competitive, we would have popped it on the air immediately,” Capus said.

Authorities still hadn’t fully examined Cho’s DVD and it wasn’t until after 6 p.m. that NBC had an official OK to show some of his filmed message. NBC’s “Nightly News” aired at 6:30 p.m. Except for one still picture aired earlier on MSNBC, that broadcast was the first to show extensive details of what NBC received.

“We are sensitive to how all of this will be seen by those affected,” said NBC anchor Brian Williams. “We know we are in effect airing the words of a murderer.”

NBC’s evening-news competitors, ABC’s “World News” and the “CBS Evening News,” managed to swiftly air portions of what NBC released only minutes after it came on the air.