The 26-year-old behind America's latest mass shooting at a college in rural Oregon, appears to have been a gun enthusiast who hoarded an arsenal of weapons and was obsessed with religion.
Though police have yet to formally name him, the gunman behind the murder of nine people at Umpqua Community College in Roseburg, has been widely identified as 26-year-old Chris Harper Mercer.
As a portrait of the shooter - who died in the carnage - began emerging on Friday, authorities said they had recovered 13 weapons belonging to him, including six at the school.
Celinez Nunez, an agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives, told a press conference on Friday that a flak jacket with steel plates and five magazines were also found laying next to a rifle at the school.
The rampage on Thursday in the close-knit rural community prompted an impassioned new plea for gun control by President Barack Obama who said Americans had become "numb" to the horror of mass shootings.
UN Secretary General Ban Ki-moon added his voice to calls for action to curb gun violence saying it was taking an "appalling toll" on American society.
Authorities said they were still trying to determine what prompted the killings. Several reports said Mercer, who apparently had no ties to the college, may have been seeking notoriety.
"He appears to be an angry young man who was very filled with hate," the New York Times quoted an unnamed law enforcement official as saying.
Another official told the Los Angeles Times that the young man, who lived with his mother, was obsessed with guns and religion and had leanings toward white supremacy.
Witnesses have said that he demanded to know his victims' religion before gunning them down.
"They would stand up and he said 'Good, because you're a Christian, you're going to see God in just about one second'," Stacy Boylan told CNN, relaying his daughter Ana's account. She survived by playing dead.
Mercer's father Ian, reached by reporters in Los Angeles, would only say he was shocked.
"It's been a devastating day," he said.
In Roseburg, where many have friends or relatives among the college's 3,300 students, large crowds turned out for a candlelight vigil for the victims, who have yet to be publicly identified.
Stories of heroism also began to emerge, among them that of army veteran Chris Mintz who was seriously injured after charging the gunman.
Mintz, who was studying at Umpqua to become a fitness trainer, threw himself against the classroom door to prevent Mercer from entering, his family said.
The gunman managed to blast his way in, shooting Mintz in the back, abdomen, hand and legs.