NBC had a number of guidelines for what radio shows could and could not contain. This volume Broadcasting in the Public Interest, from 1939, outlines those rules. This first 'Standards and Practices' booklet soon became yet another standard throughout the industry. It was 6 by 9 inches and is 80 pages long.
Involuntary manslaughter usually refers to an unintentional killing that results from recklessness or criminal negligence, or from an unlawful act that is a misdemeanor or low-level felony (such as a DUI).
Many acts of mass murder end with the perpetrator(s) dying by suicide or suicide by cop. A mass murder may be committed by individuals or organizations whereas a spree killing is committed by one or two individuals.