Laroyce Tankson, 31, (inset) has been charged with murder in the death of Chad Robertson. View Full Caption Family; Chicago Police Department

COOK COUNTY CRIMINAL COURTHOUSE — Chad Robertson was running from Amtrak police Feb. 8 when one of the officers fatally shot him near Union Station, prosecutors said Friday.

The officer, 31-year-old LaRoyce Tankson, appeared in bond court Friday on charges of first-degree murder. His bail was set at $250,000.

According to prosecutors, Robertson and two other people arrived in Chicago on a bus from Memphis about 8 p.m. on Feb. 8. The three began smoking marijuana outside Union Station, 272 S. Canal St., as they waited for a bus to Minneapolis, slated to leave at 9:45 p.m.

Tankson and his partner found the three about 8:30 p.m. and let them go with a warning, Assistant State's Attorney Ahmed Kosoko said in court Friday.

But moments later, after one person retrieved luggage from inside the station, Tankson and his partner stopped the three again, prosecutors said. The officers began to pat them down, and Robertson took off running.

At that point, Kosoko said, Tankson pulled his gun, crouched down and fired a single shot toward Robertson — striking him in his shoulder.

Robertson fell to the ground, motionless, authorities said, and died from his wound a week later. According to prosecutors, Robertson was not armed, and police never found a gun on the scene.

Defense attorney Will Fahy on Friday argued that Tankson was scared for his life and acting in self-defense when he shot Robertson that night. According to Fahy, Robertson had reached for something in his pocket and turned toward Tankson as if he had a gun before Tankson opened fire.

Fahy said police found a small bag of marijuana near Roberston's body.

Robertson's relatives, who have filed a lawsuit against Tankson and Amtrak, slammed Fahy's version of events Friday.

"I'm sorry. I'm sorry. As a young black," sister Nina Robertson said before cutting herself off and collecting her thoughts. "How many times are they going to keep being able to do this to us? How many times are they going to keep saying that that was why they're killing us? It's wrong."

Nina Robertson said her brother was most likely afraid of the officers: "I'd run, too."

"They shouldn't be able to shoot people for running away," Leroy Taylor, Robertson's father, said before expressing anger at Tankson's $250,000 bail.

"That's ridiculous. I think it should've been millions," Taylor said. "I think that's ridiculous that they let him out for so little money when he murdered my son. My son ran away. He did not stop and turn around. Why would he stop and turn if he was running? ... [Tankson] killed my son, and he should be in jail."

According to Fahy, Tankson is married to a firefighter and has three young children. He's been an Amtrak officer since 2015.

According to Nina Robertson, her brother was a devoted dad and loving person who liked to draw and work with his hands.

"He was taken from us," Nina Robertson said, "and we are confident that we will get justice. We are glad today that [Tankson] was charged. We know we will get justice, and that this is just the beginning."

An attorney representing Robertson's family said Robertson was unarmed and had not committed a crime when Tankson shot him. Robertson had been traveling home to Minneapolis after going to Memphis for a family funeral when his bus stopped for a layover in Chicago.

Robertson went to Union Station to stay warm, family said, but he and a friend were asked to leave. The lawsuit contends Tankson was "very disrespectful, aggressive and called them 'motherf---ers' several times."

Robertson and a friend walked to a nearby restaurant to stay warm and saw the officer and his partner had followed them, according to the lawsuit. The officers stopped and began searching Robertson and his friend, the lawsuit says, and the officer was again "very aggressive, disrespectful and again used a great deal of profanity."

Robertson feared for his life and ran away, the lawsuit says, at which point Tankson "calmly dropped to one knee, removed his gloves, unsecured his weapon and aimed it in the direction of Mr. Robertson's back." Robertson was shot in his back while he was less than 30 feet away, the lawsuit says.

Prosecutors in court Friday estimated the distance to be 75 to 100 feet.

Tankson did not give commands before shooting his weapon, according to the lawsuit, only saying, "It's a gun out. It's a gun out."

The bullet lodged in Robertson's spine, his family said after the shooting, and he was paralyzed in the days before his death.

Amtrak in a statement Friday said it was cooperating with Chicago Police and the State's Attorney's Office.

Read the lawsuit:

Lawsuit Against Amtrak for Shooting Near Union Station by DNAinfo Chicago on Scribd