Search goes on for writer of threats
Letters made reference to Amish school tragedy
Several police departments in New Jersey and Pennsylvania and the FBI continue to hunt for the person who sent recent letters to school districts, town courts and newspapers, threatening school massacres similar to the October Amish school rampage that killed five girls in Lancaster County, Pa.
A letter to parents sent Wednesday by one of the school districts, East Windsor Regional Schools, and East Windsor police said the investigation is ongoing but no suspects have been identified. (snip)
http://www.nj.com/news/times/index.ssf?/base/news-2/1163740192174070.xml&coll=5
This is not good.
I know they can't release info, but it's hard to look for clues with no info except for one -- "made reference to Amish tragedy" (per your post).