http://www.snopes.com/info/news/sandyhoax.asp
As it turns out, a recordkeeping anomaly of sorts is at the root of the FBI report's dissonant statistics for the Sandy Hook massacre. If you followed news of the incident at the time, you may recall that Connecticut State Police (not local city or town police) managed the crime scene in the hours, days, and weeks after the event in Newtown. Accordingly, the Sandy Hook Elementary victims were included in Connecticut's statewide records, but they were not tallied as crimes of any description in Newtown in 2012. Rather, the deaths were classified under "State Police Misc." in separate records. http://www.dpsdata.ct.gov/dps/ucr/data/2012/Crime%20In%20Connecticut%20COMPLETE%202012.pdf