(CBS) — The U.S. Attorney’s Office confirmed Monday that they are investigating the death of a 17-year-old who was shot by a Chicago police officer 16 times.

Laquan McDonald, who authorities say was armed with a knife, was killed in an encounter with police on Oct. 20, 2014 near 41st and Pulaski in the Archer Heights neighborhood.

The officer who fired the shots claimed he was in fear of his life, though no other officers on the scene fired.

A lawyer for the family argues a police camera shows McDonald was no threat was trying to walk away from the officers and that the officers were waiting for a stun gun when the officer fired.

“McDonald, as I mentioned before, was walking away when he was shot and they will argue that videotape supports their version of events,” said Corporate Counsel Steve Patton.

McDonald’s mother referred CBS 2 to her attorney Mike Robbins who told us, “We reached a fair and prompt resolution without time consuming necessity of litigation. We think the city did the right thing here.”

Robbins says he hopes the feds do the right thing, too.

U.S. Attorney Zachary Fardon confirmed that the joint investigation would be led by the FBI’s Chicago office along with the Independent Police Review Authority, the U.S. Attorney’s Office, and the Cook County State’s Attorney’s Office.

On Monday, the City Council Finance Committee approved a $5 million settlement for McDonald’s family.

Robbins says he hopes the feds do the right thing, too.

A police department spokesperson told CBS 2 he couldn’t comment due to the pending investigations but confirmed the officer involved is on desk duty until the probe is complete.