Sister Wives star Garrison Brown had a significant amount of alcohol in his system when he took his own life. Autopsy results confirmed the late television personality tested positive for alcohol poisoning and had a BAC (blood alcohol content) of 0.307 percent at the time of his death. However, he did not have any drugs in his system. The report stated Brown had a medical history of being pre-diabetic and suffering from chronic migraines. The autopsy further noted his cause of death was a self-inflicted gunshot wound to his head — something the Flagstaff Police Department also said after disco…