The man who shot and killed Joe McKnight says the ex-NFL player was fueled by a mix of steroids, pain pills and weed during their fatal confrontation ... and he only pulled his gun out of fear.
Ronald Gasser filed new court docs in the murder case against him -- claiming he learned McKnight "was under the influence of marijuana, pain pills, and anabolic steroids at the time [he] attacked Mr. Gasser."
Unclear where Gasser got his information -- it seems his legal team may have had access to McKnight's toxicology results following the autopsy.
However, in the docs Gasser paints a picture of a man in full steroid rage -- saying McKnight was "violent and erratic" following an intense chase through the streets of Louisiana on Dec. 1.
Gasser says he did NOTHING that he would consider "aggressive" to provoke McKnight -- and says it was Joe who was screaming and yelling like a maniac.
Gasser says he ultimately shot Joe while "fearing for his life."
At the time of the shooting, McKnight was a pro football player in Canada -- a running back for the Saskatchewan Roughriders.
The CFL has a strict anti-steroid policy and tests players -- though it's unclear if McKnight ever tested positive for anabolic steroids.