(CNN) When Dylann Storm Roof turned 21 in April, his father bought him a .45-caliber gun, a senior law enforcement source briefed on the investigation said Thursday.

It's not known whether that handgun was used when Roof allegedly opened fire Wednesday night at a prayer meeting at Emanuel African Methodist Episcopal Church in Charleston, South Carolina, killing nine people

"You rape our women, and you're taking over our country. And you have to go," Sylvia Johnson, a cousin of the church's slain pastor, said the gunman told his victims, according to CNN affiliate WIS . She cited survivors of the shooting.

In the sparse details that have emerged about his life, none would suggest he was capable of such hatred and violence.

Dylann Roof is escorted from the Cleveland County Courthouse in Shelby, North Carolina, on Thursday, June 18.

Police in his hometown of Columbia -- about 120 miles northwest of Charleston -- obtained a warrant for his arrest in early March. He had been picked up on drug charges a few days earlier at Columbiana Centre mall, according to a police report.

Workers at two stores told mall security that Roof was acting strangely, asking "out of the ordinary questions" such as the number of sales associates and what time they left the mall, the police report said.

Roof, when confronted, "began speaking very nervously and stated that his parents were pressuring him to get a job," according to the police report. Roof told the officer he had not picked up any employment applications.

Banned from mall

Roof initially said he wasn't carrying anything illegal. But he agreed to be searched and an officer found "a small unlabeled white bottle containing multiple orange ... square strips" in his jacket, the police report said.

The bottle contained Listerine breath strips, Roof said.

The officer asked again. Roof said the strips were suboxone, which is used to treat opiate addiction, according to the police report. Roof said he got the strips from a friend.

He was arrested on a drug possession charge that day in late February, but it's unclear why the March 1 arrest warrant was issued.

On April 26, police were again called to Columbiana Centre because Roof, who had been banned from the mall for a year after his drug arrest, had returned, the police report said. The ban was extended to three years.

Roof was arrested that day in late April on a charge of trespassing; his car was turned over to his mother. The disposition of the case is unclear.

One schoolmate of Dylann Roof described him as "kind of wild" but not violent.

John Mullins, who attended White Knoll High School with Roof, told CNN on Thursday that the suspect was "kind of wild" but not violent.

"He was ... calm," Mullins said. "That's why all this is such a shock."

Mullins said Roof occasionally made racist comments although he had black friends.

"They were just racist slurs in a sense," he said. "He would say it just as a joke. ... I never took it seriously, but now that he shed his other side, so maybe they should have been taken more seriously."

Roof repeated the ninth grade at the Lexington County high school, according to Mary Beth Hill of the Lexington School District. She said he was "very transient," that he "came and went."

'Quiet, strange, very unsocial'

"He was quiet, strange, very unsocial and everyone thought he was on drugs," Graham said of the suspect, relaying the description from Emily and his sister, Darline Graham Nordone.

The niece did not recall Roof making statements related to race, Graham said.

Photos: Reactions to Charleston church shooting Photos: Reactions to Charleston church shooting Thousands of people march on the Arthur Ravenel Jr. Bridge in Charleston, South Carolina, on Sunday, June 21. People crossed the bridge, which spans the Cooper River, from Mount Pleasant to Charleston, joining hands in a unity chain to mourn the Emanuel AME Church shooting. Police arrested Dylann Storm Roof in the slayings of nine people at a prayer meeting at the church. Hide Caption 1 of 25 Photos: Reactions to Charleston church shooting Protesters stand on the South Carolina State House steps during a rally to take down the Confederate flag, on Saturday, June 20, in Columbia. Hide Caption 2 of 25 Photos: Reactions to Charleston church shooting Louise Brown walks down King Street during a "Black Lives Matter" march on June 20 in Charleston, South Carolina. Hide Caption 3 of 25 Photos: Reactions to Charleston church shooting The men of Omega Psi Phi Fraternity lead a prayer outside Emanuel AME Church, Friday, June 19. Hide Caption 4 of 25 Photos: Reactions to Charleston church shooting Young people grieve outside Emanuel African Methodist Episcopal Church in Charleston, South Carolina, on June 19. Hide Caption 5 of 25 Photos: Reactions to Charleston church shooting Parishioners applaud during a memorial service on Thursday, June 18, at Morris Brown AME Church in Charleston, South Carolina. Hide Caption 6 of 25 Photos: Reactions to Charleston church shooting Olina Ortega, left, and Austin Gibbs light candles at a sidewalk memorial in front of Emanuel AME Church on June 18. Hide Caption 7 of 25 Photos: Reactions to Charleston church shooting The Rev. Jeannie Smalls becomes emotional during a prayer vigil held at Morris Brown AME Church on June 18. Hide Caption 8 of 25 Photos: Reactions to Charleston church shooting A woman places flowers outside the church on June 18. Hide Caption 9 of 25 Photos: Reactions to Charleston church shooting Mourners gather for a community prayer service at Second Presbyterian Church in Charleston on June 18. Hide Caption 10 of 25 Photos: Reactions to Charleston church shooting Walter Jackson, the son of Susie Jackson who died in the church shooting, recalls stories about his mother with his niece Cynthia Taylor at Jackson's home in Charleston on June 18. Hide Caption 11 of 25 Photos: Reactions to Charleston church shooting The Rev. Al Sharpton wipes away a tear after praying outside the Emanuel AME Church in Charleston on June 18. Hide Caption 12 of 25 Photos: Reactions to Charleston church shooting People sit on the steps of Morris Brown AME Church in Charleston while services are held June 18. Hide Caption 13 of 25 Photos: Reactions to Charleston church shooting A woman wipes her eyes at a makeshift memorial near the Emanuel AME Church in Charleston on June 18. Hide Caption 14 of 25 Photos: Reactions to Charleston church shooting The Rev. Keith McDaniel, pastor of Macedonia Missionary Baptist Church, is surrounded by others in prayer on June 18 in Spartanburg, South Carolina. Hide Caption 15 of 25 Photos: Reactions to Charleston church shooting Tyler Francis, right, hugs Shondrey Dear after praying together June 18 at a makeshift memorial near the Emanuel AME Church. Hide Caption 16 of 25 Photos: Reactions to Charleston church shooting A group of women prays together at a makeshift memorial on the sidewalk in front of the Emanuel AME Church on June 18. Hide Caption 17 of 25 Photos: Reactions to Charleston church shooting President Barack Obama, accompanied by Vice President Joe Biden, pauses while speaking in the Brady Press Briefing Room of the White House in Washington, June 18, on the church shooting in Charleston. Hide Caption 18 of 25 Photos: Reactions to Charleston church shooting Members of the U.S. Congress gather in front of the Capitol Building in Washington on June 18, during a moment of silence for the nine killed in a church shooting in Charleston, South Carolina. Hide Caption 19 of 25 Photos: Reactions to Charleston church shooting South Carolina state Sen. Vincent Sheheen gets emotional on June 18 as he sits next to the draped desk of Sen. Clementa Pinckney at the statehouse in Columbia, South Carolina. Pinckney was one of the nine people killed in the church shooting. Hide Caption 20 of 25 Photos: Reactions to Charleston church shooting Charleston resident Noah Nicolaisen kneels at a makeshift memorial down the street from the church on June 18. Hide Caption 21 of 25 Photos: Reactions to Charleston church shooting Kim Hamby prays with her daughter Kayla as they lay flowers at a makeshift memorial in Charleston on June 18. Hide Caption 22 of 25 Photos: Reactions to Charleston church shooting A man leans against a light pole as he visits a memorial in Charleston on June 18. Hide Caption 23 of 25 Photos: Reactions to Charleston church shooting Chaplain James St. John leads senators in prayer June 18 at the statehouse in Columbia. Hide Caption 24 of 25 Photos: Reactions to Charleston church shooting Sandra Bridges lays a card at a memorial on June 18. Hide Caption 25 of 25

"I just think he was one of these whacked-out kids. I don't think it's anything broader than that," said Graham, who is running for president. "It's about a young man who is obviously twisted."

On Wednesday night, the white and slightly built gunman was at the historic African-American church for about an hour, attending a meeting with his eventual victims , before the massacre, according to Charleston police Chief Greg Mullen.

Witnesses told investigators the gunman stood up and said he was there "to shoot black people," a law enforcement official said.

Investigators are looking into whether Roof had links to white supremacist or other hate groups, a law enforcement official said. There's no indication so far that he was known to law enforcement officials who focus on hate groups.

In an image tweeted by authorities in Berkeley County, South Carolina, Roof is seen wearing a jacket with what appear to be the flags of apartheid-era South Africa and nearby Rhodesia, a former British colony that a white minority ruled until it became independent in 1980 and changed its name to Zimbabwe.

Woman spared by shooter to give account?

A female survivor told family members that the gunman told her he was letting her live to tell everyone else what happened, Dot Scott, president of the local branch of the NAACP, told CNN.

JUST WATCHED Images show moments before Charleston church shooting Replay More Videos ... MUST WATCH Images show moments before Charleston church shooting 01:06

Scott said she had not spoken to the survivor directly but heard this account repeated at least a dozen times as she met with relatives of the victims Wednesday night.

"No one in this community will ever forget this night and ... the pain and the hurt this individual has caused this entire community," Mullen said.

Charleston Mayor Joe Riley said the suspect was "filled with hate and with a deranged mind."

The man is a "no-good, horrible person," he said. "Of course we will make sure he pays the price for this horrible act."