He then was assisted by his mother and others in hiding evidence, according to court documents.
Details of the killing were given Thursday by Sheriff Ricky Bishop at a news conference.
Investigators learned that during the party eight months ago that a tall, light-framed individual with a distinct speech impediment had been pushed down or ended up on the ground, court documents state.
The individual got up from the ground, pointed a pistol into the crowd and discharged several gunshots, documents state.
One gunshot hit Kirkland.
Arrests are made
George Girard Johnson Jr., 17, of Abilene was taken into custody Wednesday at Woodson Center For Excellence on an arrest warrant for a charge of murder in connection with Kirkland s death, Bishop said.