After Ky. Officer Ambushed, Threats of More Cop Killings FBI, state police investigating By Evann Gastaldo, Newser Staff Posted Jun 11, 2013 2:11 PM CDT 27 comments Comments Law enforcement officers stand at parade rest following the funeral service of Officer Jason Ellis Thursday, May 30, 2013, at Parkway Baptist Church in Bardstown, Ky. (AP Photo/Timothy D. Easley) (Newser) – Police in Bardstown, Kentucky, are living under a dire threat: The police department chief says he received a letter Thursday warning that "there were more officers that would go down like the first one"—"one" being an apparent reference to Officer Jason Ellis, who was shot to death after stopping to remove tree limbs that investigators think were put in the roadway on purpose. The police chief says at least one additional threat came in by phone, and so far his department doesn't know who's behind them, the Courier-Journal reports. WHAS-11 reports that multiple letters, note cards, and postcards have been coming in; the Kentucky State Police and the FBI are investigating, though the chief says he doesn't believe the threats are credible. Last week, the AP reported that detectives were questioning gang members about the ambush on Ellis, in part due to posts that appeared on social media. Ellis had arrested the leader of a gang in January on assault and other charges; he's now serving 10 years but maintains that nobody in his gang is responsible.