Sharon Jones, whose son Malek Dayvon Mercer was shot in 2015, says waiting is the hardest part. “But I’m not going anywhere. I am going to sit here until my son gets justice.” (Bonnie Jo Mount/The Washington Post)

Each time Sharon Jones sees the D.C. courthouse Metro subway stop, her heart begins to pound and she fights to catch her breath. She has become familiar with the trek from the station to the large courthouse, through security and up to the third-floor courtroom.

This week, Jones will be taking the same walk for the third trial of the man who fatally shot her 15-year-old son, Malek Dayvon Mercer.

In two previous trials, D.C. Superior Court jurors were unable to reach verdicts on murder charges against Derryck Decuir, 26, who said he shot Malek in self-defense as the two stepped off a Metro bus in the early hours of June 16, 2015.

As a third jury considers the case, Jones will again be there. She expects to testify about her son and then sit in the gallery as prosecutors put on mounds of evidence. Once again, she will see graphic crime-scene and autopsy photos and hear heart-wrenching testimony from Malek’s friends who were with him the night he was shot. And once again, she is prepared to wait as jurors deliberate.

“That’s the most difficult part,” Jones said. “The waiting is more stressful than being in the courtroom and watching the trial. But I’m not going anywhere. I am going to sit here until my son gets justice.”

The trial is scheduled to begin Monday in front of Superior Court Judge Craig Iscoe. It's rare for federal prosecutors in the District to try a murder case more than twice, a spokesman for the U.S. attorney's office said.

Malek Dayvon Mercer was 15 when he was fatally shot in Southeast Washington in 2015. (Family photo)

Jones, 46, who has three surviving children and is a grandmother of three, works as a customer service representative for the Washington Metropolitan Area Transit Authority.

Although the hours in the courthouse have been painful, she said there also have been unexpected moments of solace. She became friendly with other mothers who have lost sons to gun violence and waited for answers in other courtrooms.

One was Rashida Washington, who was with her 15-year-old son, Davonte Washington, when he was killed in 2016 as the family was out shopping in preparation for Easter. They were on the Deanwood Metro platform when an older teen walked up to Davonte and shot him once in the chest because he believed Davonte — who was unarmed — gave him a threatening look. The killer was found guilty at trial.

Washington said Jones calmed and comforted her during the trial in her son’s death.

“This is something that only a person who has been through it themselves can help you get through emotionally,” Washington said. “I can’t imagine having to sit through that twice, let alone three times. I pray this all comes to a head and she finds peace.”

No matter what the verdict is in Decuir’s latest trial, he will not walk free. Although two juries could not agree whether he committed murder, the first jury did find him guilty of a gun crime and other counts.

The first trial in Malek’s death was in 2017. Prosecutors argued that Decuir shot Malek after trying to rob him of his red designer Versace belt, Nike Air Force 1 sneakers and items inside his duffle bag.

Decuir’s public defenders offered a far different account. They said that Malek was carrying a gun in a duffle bag and that he pulled it out when he wrongly believed Decuir was going to rob him. Decuir, his attorneys argued, saw the gun and, in fear, pulled out his gun and shot Malek.

No gun was found on Malek’s body. Defense attorneys said Malek’s friends, who were with him when he was shot, grabbed the weapon.

That jury acquitted Decuir of the attempted robbery charges and first-degree premeditated murder, but failed to reach a unanimous verdict on a second-degree murder charge. The judge declared a mistrial on the murder charges.

The panel did find Decuir guilty of possessing a handgun as a felon. At the time of Malek’s shooting, Decuir was on probation for a 2014 conviction in Prince George’s County for carrying a pistol without a license.

Decuir was also convicted of evidence tampering and obstruction of justice. Prosecutors said Decuir, while in the D.C. jail awaiting trial in Malek’s case, used his phone calls to encourage friends to hide his guns and to lie to authorities.

In August, Judge Hiram Puig-Lugo sentenced Decuir to 23 years in prison, the maximum sentence according to District guidelines. Puig-Lugo’s anger during the sentencing was palpable. “I know the government’s theory was this was a robbery gone bad, but I sat through that evidence. That was not a robbery gone bad. That was somebody being disrespectful to you in front of your boys,” Puig-Lugo said. “I’m aware that Mr. Mercer had that shotgun in a duffle bag. But let’s be clear. You were the one who followed him. He didn’t follow you. You were the one who shot him in the back.”

Prosecutors decided to try Decuir a second time on the murder count. During that trial last year, prosecutors scrapped their attempted robbery theory. Instead, they argued that Decuir killed Malek out of anger and retaliation because Malek laughed at him during a bus ride. Prosecutors said Decuir’s friends, who were on the bus, teased and joked.

Decuir maintained his self-defense argument.

Jones said she never knew her son to even hold a gun, let alone possess one. But even one of Malek’s friends testified that she had seen him with a weapon.

“I don’t know what to believe anymore. But I know my son is dead and he killed him,” Jones said.

The jury once again was unable to reach a verdict on the murder charge.

Jones said she was “numb” during the first trial. During the second trial, the numbness had worn off. She remembers bursting into tears when she saw a photo of her son lying on the ground and hearing the 911 call his friend made. Her doctor had prescribed her anti-anxiety and anti-depression medication for the previous trial. She hopes she will not need the medication for this trial.

Jones said she hopes for a guilty verdict on the murder charge this time but knows that may not happen.

“I have more anxiety this time. I don’t know how this is going to go,” she said. “I ask myself every day, ‘How am I going to get through this?’ ”