There was a lull of more than two hours between shootings
Virginia's governor, Tim Kaine, has appointed an independent panel to investigate Monday's gun rampage at Virginia Tech in which 33 people died.
The six-member team includes former Homeland Security chief Tom Ridge.
The panel will study the treatment of gunman Cho Seung-hui in the period preceding the shootings, as well as events on the day itself.
Officials have been accused of ignoring signs that Cho, who had been identified as mentally ill, was a danger.
Eight students injured in the assault are still being treated at Montgomery Field Hospital, close to the university campus.
Seventeen people were treated for injuries after the shooting, with four undergoing major surgery.
Virginia Tech Provost Mark McNamee has announced that the 27 students that Cho killed will all receive posthumous degrees.
The first funeral ceremonies for those killed were held in Virginia on Thursday. Egyptian Waleed Mohammed Shaalan and Indonesian Partahi Lumbantoruan, both doctoral civil engineering students, will also have funeral ceremonies in their home countries.
On Friday, family members gathered in Israel for the funeral of mathematics professor Liviu Librescu.
Two people were killed at the West Ambler Johnston Hall, a university dormitory, at 0715 on Monday.
Two hours later Cho killed 30 students and teachers, plus himself, at the Norris Hall complex across campus.
Though police have not definitively linked Cho to both sets of shootings, they say the same gun was used at both locations.
Questions are being asked about the response to the first shootings and whether putting the campus on a full lockdown earlier could have saved lives.
Lesson to be learnt
Mr Kaine said the investigation would not seek to lay blame, but to ensure that such a tragedy could not happen again.
The panel, which will be led by former Virginia police chief Gerald Massengill and include security and education officials and a psychiatrist, will study what mental health treatment Cho received and if more could have been done to avert Monday's violence.
It will seek to discover "everything we know about the young man who was the perpetrator", Mr Kaine said.
"What were the warning signs? Who was warned? What was done?"
Families cancelled an appearance on NBC over Cho's video airing
Police have already revealed that Cho, who moved to the US with his family from South Korea in 1992, was admitted to a mental health unit in late 2005.
He was sent for evaluation after two female students made complaints against him, they said.
The complaints by students against Cho were made in November and December 2005. Around the same time, Cho's English teachers raised concerns over his writing and general behaviour.
In the aftermath of the shootings, teachers and fellow students have spoken of Cho's extreme moods, violent writings and unpredictable behaviour.
In the two-hour lull between killings, Cho sent a package to US network NBC containing 28 video clips 1,800 words of text and 43 photos, 11 of them showing Cho aiming handguns at the camera.
Police have criticised the decision by NBC to air the clips.
"We're rather disappointed in the editorial decision to broadcast these disturbing images," police superintendent Colonel Steve Flaherty said.
Police said the videos - showing an angry Cho ranting and pointing guns at the camera - added little to their investigation.
NBC defended its decision to use Cho's videos, saying in a statement: "We have covered this story - and our unique role in it - with extreme sensitivity, underscored by our devoted efforts to remember and honour the victims and heroes of this tragic incident."
However, some relatives of those killed cancelled planned interviews with NBC, angry over the network's decision.