The Cook County state’s attorney’s office charged LaRoyce Tankson, an Amtrak police officer, with murder on Friday.

The arrest stems from a fatal shooting that took place near Union Station on Feb. 8. Tankson, 31, opened fire in fear of his life after claiming that Chad Robertson, the victim, turned toward him and pulled something from his pocket, the Chicago Tribune reports.

Robertson was taking a bus from Memphis to Minneapolis and had a layover in Chicago. During that time, Tankson found the victim and two others smoking weed outside of Union Station. The group followed his request to stop and Robertson, then apologized.

However, that wasn’t the end of their encounter.

Later in the night, Tankson and his partner stopped and searched Robertson and two others who were with him. After patting them down, Tankson felt what he thought was a hard metal object. At that point, Roberston proceeded to run and that’s when the officer shot him.

According to the prosecutor, Tankson “assumed a crouching firing stance” and fired once hitting Robertson from about 75 to 100 feet away.

The shooting left Robertson, 25, paralyzed and he died from his wounds a week later. An autopsy from the medical examiner confirmed that he had been shot in the back.

Robertson’s family filed a federal lawsuit on his behalf alleging that Tankson followed him and his friends to a nearby restaurant near Union Station during the layover. The suit also claims that the officers conducted an illegal search and Robertson and companions were illegally detained.

Chicago police spokesman stated that Robertson was unarmed and had cash and narcotics on him.

Tankson and officers involved in the incident have been placed on administrative assignment. Judge Maria Kuriakos Ciesil set bond at $250,000 during a hearing .