Ketrell Jamon Hawkins, of Tabb Drive, Gaston, was taken into custody Monday and jailed without the opportunity for bond.
His faces identical charges as Rodney Jamall Joyner, 18, with the exception of going armed to the terror of the public, Chief Andy Jackson said.
Joyner was taken into custody Sunday evening.
Jackson said Hawkins was arrested on warrants drawn up by investigators. He declined to discuss the alleged role of Hawkins in the murder of the 20-year-old Cotton, who was shot in the face, and the shooting of a still unnamed second person who was shot in the back as he sat in a vehicle with Cotton on Gordon Drive near the Oak Street intersection.
The second shooting victim remains in critical, but stable condition, at an undisclosed medical facility.
Jackson declined comment on the alleged relationship between Hawkins and Joyner and also declined comment on motive.
He would not discuss what the men were allegedly robbed of the day of the murder. Robbery with a dangerous weapon and conspiracy charges are included in the counts filed against both the teenagers.
Jackson said more arrests are expected.