The video shown in court also showed the worshipers entering the church on that tragic night.
Shocking video taken moments after the 2015 Charleston church massacre shows Dylann Roof, with blood on his shirt and a gun in his hand, leaving the scene.
The footage, taken from a camera at the front door of the church, shows Roof calmly exiting the church while holding the .45-caliber Glock.
Read: Dylann Roof's Mom Suffers Heart Attack in Courtroom as Attorneys Describe the Massacre
The video was played at Roof's trial Wednesday, along with a haunting clip of parishioners at Mother Emanuel African Methodist Episcopal Church greeting each other and hugging as they arrived at the Bible study some 30 minutes before more than 60 bullets claimed nine innocent lives.
Among the arriving worshipers is Roof, seen adjusting his sweatshirt with the gun believed to be hidden underneath.
CBS News correspondent Mark Strassmann said Roof's mother was so distraught during the prosecution’s opening statement that she suffered a heart attack in the courtroom.
"I saw the EMTs bring in a gurney into the courthouse to bring her out. Apparently, she had a heart attack. I don’t know how well she is doing," he told Inside Edition.
Amelia Cowles fell ill at the start of her son's federal death penalty trial Wednesday. She collapsed and repeatedly apologized as her family and court officials came to her aid, The Associated Press reported.
For the families of the victims, relieving the nightmare in court has been a mournful experience.
Strassmann recalled to Inside Edition: "When a couple of survivors testify, you can hear sobbing in the courtroom, some even had to leave the courtroom. It is horrific for these families to relive the last awful moments in the lives of their loved ones."
Roof is charged with 33 federal counts, including hate crimes in the case. He has pleaded not guilty. The defense has said he is willing to plead guilty if the death penalty is taken off the table.
Read: Dylann Roof Ruled Competent to Stand Trial for Church Massacre
Roof also faces nine murder charges at the state level. He faces another death penalty case next year.
In a written manifesto and in his interview with the FBI, U.S. attorney Jay Richardson said the young man “confessed fully” to what happened inside the historic church.
“I went to the church that night. I did it. I killed them,” Roof admitted, according to Richardson.
