Memorial services have been held across the US for the 32 people gunned down at Virginia Tech university last week.
Church bells rang throughout the US to commemorate the victims
Prayers were said at the National Cathedral in Washington during a special evening service.
Virginia Tech classes resume on Monday and university officials are due to mark the occasion by tolling a bell for each of the victims.
Student Cho Seung-hui killed 32 people and himself, in the deadliest shooting rampage in modern US history.
The National Cathedral service began with a procession of officials and Virginia Tech graduates carrying a candle for each person who died.
One candle represented the South Korean-born gunman, who came to the US with his family in 1992.
The Reverend Howard Anderson drew comparisons between Cho's bloody rampage and the carnage in Iraq, but he also called for compassion for the gunman.
"He too is a child of God, and a victim of the social stigma attached to depression and other mental illness which prevents people from getting the help they need," Mr Anderson said.
In a similar sign of reconciliation, mourners at Virginia Tech have added a 33rd stone representing Cho's life to a victims' memorial on the school's drill field.
Throughout the US, church bells rang and there were a number of services around the town of Blacksburg, where the university is located.
Police investigating the massacre have said that Cho, 23, apparently bought empty ammunition clips from auction website eBay about three weeks before the shooting.
A stone to remember Cho has been added to a makeshift memorial
EBay spokesman Hani Durzy said the sale was legal and that the company has co-operated with the investigations.
Police are also examining computers in Cho's dorm room and seeking his mobile phone records.
A six-member independent panel - including former homeland security chief Tom Ridge - will also examine how authorities reacted to the crisis, amid claims officials ignored warning signs that Cho, who had been admitted to a mental health unit in late 2005, was a danger.
Cho's family has expressed shock and sorrow for the "horrible and senseless act", saying they were living a nightmare since the massacre.
Cho's killing spree began at 0715 last Monday, when two people were killed at West Ambler Johnston Hall, a university dormitory.
Two hours later he killed 30 students and teachers, plus himself, at Norris Hall across campus.
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.