Jury selection has begun in the murder case against a man and a 15-year-old charged with shooting and killing an Army Reservist during an armed robbery attempt in Atlanta on the night after Christmas in 2013, authorities said.

Qutravius Palmer, 24, and the juvenile, who is not being identified because of his age, are accused of killing Xavier Arnold, 21, as he walked with his girlfriend and another friend along a bike trail near Rogers Street in the Kirkwood neighborhood.

Palmer and the juvenile confronted the three friends and demanded their belongings, and when Arnold resisted, he was shot in the back of the head, the Fulton County District Attorney's Office said. Arnold died at Grady Memorial Hospital. His friend Ibrahim Sanusi was shot in the leg and survived.

The two suspects are charged with murder, felony murder and aggravated assault. They were identified from a photo lineup, the district attorney’s office said, and eventually turned themselves in to authorities.

Arnold, an aspiring artist who studied art at the Savannah College of Art and Design, and his friends were planning to take pictures of graffiti along the trail when the incident occurred.

Known as “X,” Arnold served three years in the Georgia National Guard. His memorial service at New Birth Missionary Baptist Church in Lithonia included military honors provided by members of the Guard. He was a 2010 Chamblee High School graduate.

Opening statements in the case, which is being tried in DeKalb County Superior Court, are expected to start Tuesday.