Police were called to the Hal Jensen Recreation Center on March 3 after receiving reports about a shooting in the men's restroom.
When officers arrived, 20-year-old Jacob Allen of Flagstaff was found dead at the scene.
Fifteen-year-old Fernando Enriquez of Flagstaff was recently arrested after being released from Flagstaff Medical Center. Enriquez was also shot during the incident but is now facing homicide charges. He is being charged as an adult, police said.
Police originally believed the incident was a drive-by shooting but have since learned that it was not a random act.
Authorities said two firearms were involved in the shooting, however, officers have only been able to locate one so far.
An investigation is ongoing and no additional information was released.