The 21-year-old white gunman who slaughtered nine people at a Charleston, South Carolina, church was previously jailed in March on a drug charge, NBC affiliate WIS-TV reported.
He is suspected of gunning down nine people at the historically black Emanuel African Methodist Episcopal Church on Wednesday night while sitting in on a Bible study class. Three others survived.
He was captured by police Thursday morning, sources said.
Police said Roof fled after the shooting just after 9 p.m. ET in a black Hyundai Elantra.
Charleston officials are investigating the shooting as a hate crime. The Justice Department also announced it is opening a parallel civil rights investigation into the case.
While the manhunt intensified Thursday, Roof's uncle told Reuters that he recognized the man in the surveillance photo as his nephew.
"The more I look at him, the more I'm convinced that's him," said Carson Cowles, 56.
Cowles told Reuters that authorities were at Roof's home, and that his nephew had been given a .45-caliber handgun from his father for his birthday in April.
This article originally appeared on NBCNews.com.