Had Anthony Mazella, 20, been convicted of the latter he would be facing life without parole. The maximum for his conviction is five years.
The jury split 10-2 for the lesser crime in the July 24, 2009 shooting death of Jeral Matthews of Clinton is a dope deal gone bad.
Two others are awaiting trial in the case.
Two other men, Johnny Barnes of Clinton and Andrew Robertson of Hammond, await trial on charges of principal to first-degree murder in the case.
During his trial, no one contested Manzella shot and killed Matthews with a single round from .40-caliber Glock semiautomatic pistol during a drug deal. The defense claimed the killing was self defense.
Robertson and Manzella traveled to Clinton to purchase a pound of marijuana, according to testimony.
However, police recovered only a small amount of marijuana instead of the allegedly agreed upon pound of it. The state argued Manzella could have shot Matthews for reneging on the deal.
Defense attorneys claimed Matthews attempted to rob Robertson and Manzella with the assistance of Barnes. During the attempted robbery in which Matthews is alleged to have been holding an AK-47, Manzella was struck in the head and knocked over a bed by Matthews. When Manzella rose from the ground, fearing for his safety and that of Robertson, he shot Matthews in self defense, the defense contended.