Cho killed at least 32 people before shooting himself Monday on the Blacksburg, Va., campus.
After turning over the original documents -- which arrived at NBC News headquarters in New York Wednesday -- to federal authorities, the decision to air portions of the 27 video clips, 43 stills and one video clip in the 23-page statement fell to NBC News President Steve Capus, The Washington Post said Thursday.
"We tried to be sensitive to the families involved and to the investigation," Capus said. The network could be viewed as offering Cho a platform to air his grievances or as providing a type of closure to those who "want to know why," he said.
Capus said Virginia State Police officials asked NBC to delay airing the material until they reviewed it.
Prefacing their airing on "NBC Nightly News" Wednesday, anchor Brian Williams said, "We are sensitive to how all of this will be seen by those affected, and we know we are, in effect, airing the words of a murderer here tonight."