[Dystopos]

"The Arrestee Drug Abuse Monitoring program (ADAM) measures the extent of drug and
alcohol use in the high-risk population of people who have been arrested and booked as
adults in city and county detention facilities operated by local police and sheriff
departments." For Birmingham, Alabama in 2003, 530 arrestees were interviewed and 87.5% of those tested by urinalysis. 66.1% of adult male arrestees tested positive for at least one illegal drug: 34.3% tested positive for crack or powder cocaine, 44.6% for marijuana, 1.2% for methamphetamine, and 8.3% for heroin.

This isn't just murder arrests, of course. I couldn't immediately find a breakdown of homicides by "contributing factor" or motive, though I know the CDC collects those statistics for the FBI. I know that when I lived in New Orleans and the murder count soared well over 300 that the Times-Picayune published statistics that the overwhelming majority of murders were the result of illegal business deals and lover's spats. Very few victims were targeted from outside the perpetrator's immediate circle. Two factors that tend to mirror homicide rates are unemployment and temperature.