By Khushbu Shah, Martin Savidge and Catherine E. Shoichet

CNN

CHARLESTON, South Carolina (CNN) -- Dylann Roof's federal trial is nearing its final chapter.

Closing arguments in the case are expected Tuesday. Jury deliberations could begin soon afterward. Jurors are tasked with deciding whether Roof will get a death sentence or life in prison without the possibility of parole.

The prosecution and defense rested on Monday, bringing to a close days of heartbreaking testimony from family and friends of victims who were killed in the June 2015 massacre at Emanuel African Methodist Episcopal Church in Charleston, South Carolina.

Roof, an avowed white supremacist, killed nine people at the historically black church.

Prosecutors argue that he's a calculating killer who deserves the death penalty because of his motive, his lack of remorse and the shooting's impact on the victims' families.

Evidence they've presented has included chilling writings from a jailhouse journal Roof wrote after the attack.

"I would like to make it crystal clear. I do not regret what I did," Roof wrote in the journal. "I am not sorry. I have not shed a tear for the innocent people I killed."

Friends and relatives of victims slain in the shooting gave emotional testimony in court, some of them sobbing on the stand.

As they made their case, prosecutors played haunting recordings of the victims preaching, praying and singing.

Will Roof make a closing argument?

Roof, 22, has been representing himself in court since this phase of the trial began.

On Monday, he told the judge he didn't want to testify, then asked whether his attorney could assist him in closing arguments.

US District Judge Richard Gergel granted that motion. It's unclear whether Roof will be speaking to jurors directly again in court.

Roof has not questioned witnesses, but filed several motions objecting that their testimony had been too emotional.

In his opening statement, he told jurors that he doesn't have mental health problems.

Facing the death penalty

If jurors in this trial decide to spare Roof's life, he could still face a death sentence. He's also set to be tried on state murder charges, and prosecutors have said they'll also seek the death penalty in that case.

Boston Marathon bomber Dzhokhar Tsarnaev was the last person to get a federal death sentence. He's one of 62 federal prisoners awaiting execution, according to the Death Penalty Information Center, a Washington-based nonprofit.

Only three federal inmates have been executed in the United States since the federal death penalty was reinstated in 1988 after a 16-year moratorium:

• Oklahoma City bomber Timothy McVeigh on June 11, 2001, six years after he killed 168 people.

• Juan Raul Garza on June 19, 2001, eight years after he was convicted of running a marijuana drug ring and killing three people.

• Louis Jones on March 18, 2003, eight years after he kidnapped and murdered 19-year-old Army Pvt. Tracie McBride.

CNN's Khushbu Shah and Martin Savidge reported from Charleston. CNN's Catherine E. Shoichet wrote the story in Atlanta. CNN's Darran Simon, Steve Almasy and Ralph Ellis contributed to this report.