The president of NBC News said the decision to images, writings and video of Virginia Tech shooter Seung-Hui Cho last week was "good journalism".
Cho sent NBC a package with the materials between the first and second bursts of gunfire April 16 that ended with 33 dead, including Cho himself.
NBC News President Steve Capus, who appeared with NBC Nightly News anchor Brian Williams on Tuesday's broadcast of "The Oprah Winfrey Show," acknowledged images that "wallpapered" the media were uncomfortable to view.
"Sometimes good journalism is bad public (relations)," Capus said. "These are very difficult decisions."
"Remember, this was days after the incident," he said. "The largest question out there was 'Why?"'
Capus said the package from Cho arrived at the New York headquarters at 11 a.m. (1500 GMT) two days after the shooting. NBC officials sifted through the material and waited until 6 p.m. (2200 GMT) to air parts of it.
"We hit the brake pedal," Capus said.
He said NBC decided to show two minutes of 25 minutes of video, seven of 43 photographs and 37 sentences of 23 pages of written material.
Williams, who said the repeatedly shown images became too much for his family to watch, said the story was too important not to air.
"However uncomfortable it is, it proves this was journalism," Williams said. "This was news and a material advance in the story."