The federal death penalty trial for Dylann Roof, the white man accused of killing nine black members of Charleston's Emanuel AME Church in a racially motivated attack, will begin on November 7, a judge said on Tuesday.

US District Judge Richard Gergel set the federal proceedings ahead of a state capital punishment trial scheduled for January.

Gergel said up to 1,500 people from across South Carolina could be called as possible jurors for the federal trial.

Federal prosecutors said last month that they intended to pursue capital punishment for Roof should he be convicted of the June 17, 2015, killings during a Bible study at Emanuel AME Church.

In court, Roof's federal attorneys reiterated that he would be willing to plead guilty if capital punishment was ruled out.

"Our plea offer has not been withdrawn and will never be withdrawn," lawyer David Bruck told the hearing.

State prosecutors had signaled their plans to seek the death penalty last year, making the case a rare instance of a defendant facing the death penalty in federal and state courts at the same time.

Roof, 22, faces different charges in each. State prosecutors charged him with murder and attempted murder, while federal prosecutors charged him with 33 counts including hate crimes, obstruction of religion, and firearms offenses.

Jury selection in the state trial is due to start in early December, which could overlap with the federal proceedings. Gergel estimated on Tuesday that jury selection and the guilt and penalty phases of the federal trial could last six weeks.

"The most important thing is bringing justice to these families and this case as efficiently and as quickly as possible, still getting it done right," state prosecutor Scarlett Wilson said after the court hearing in Charleston.

Roof and more than a dozen family members of the shooting victims attended the hearing, held ahead of the first anniversary of the shooting next week.

Two days after the killing spree, the relatives of those killed at Emanuel AME Church in Charleston stood up one by one and offered the suspected murderer their forgiveness.

"You took something very precious from me, but I forgive you," Ethel Lance's daughter told Roof at his bond hearing. "It hurts me. You hurt a lot of people, but may God forgive you."

"We would like you to take this opportunity to repent," said Anthony Thompson, grandson of Myra Thompson, one of the nine victims. "Repent. Confess. Give your life to the one who matters the most, Christ, so he can change your ways no matter what happens to you and you'll be OK."

The following day Cynthia Hurd's husband, Arthur, said: "What I can say to that young man is that in time I will forgive you."

A number of remembrance events are planned in Charleston, including a Bible study and service at the church and a service at the arena where President Barack Obama gave the eulogy for the church's slain pastor.

Bernice King, daughter of civil rights leader Martin Luther King Jr., will be the keynote speaker at an event in the city on June 18.

Additional reporting by Reuters.