A man has pleaded guilty to gang activity in connection with the 2010 shooting death of a Chamblee 11-year-old.

Alexander Sidloskas, one of three teens arrested for the Feb. 11, 2010 fatal shooting of Nicholas Sheffey, entered his plea Tuesday in DeKalb County Superior Court. He will serve 50 years in prison, his attorney said.

In a 59-count indictment, Sidloskas, Cody Dane Bauer and Stedmund Jermaine Anthony were accused of malice murder, felony murder, evidence tampering, several counts of aggravated assault and a litany of illegal gang activity charges.

Sidloskas, who was 19 at the time of the incident and was not present at the home where Sheffey was shot, pleaded guilty to four counts of violating the state's street gang and terrorism prevention act.

"He's horribly remorseful and feels just terrible," Sidloskas' attorney Robert Meier told The Atlanta Journal-Constitution. "He holds himself responsible for his part in all this."

Police say Sidloskas enlisted the help of Anthony and Bauer to retaliate against Sheffey's older brother, who was accused of committing a home invasion sometime prior to the shooting.

Anthony drove Bauer to the home, police said, where Bauer allegedly fired seven times at the house.

Sheffey was asleep in his bunk bed and was struck in the head, authorities said. He later died at a nearby hospital.

Bauer and Anthony remain in DeKalb County jail awaiting trial.