Spokesman : The Department of Homeland Security (DHS) is working with the U.S. Attorney's Office for the Eastern District of Virginia to investigate a possible threat against our nation's critical infrastructure. A medical examiner ruled Mary Kennedy died of asphyxiation due to hanging . Kennedy family members purchased some 50 plots surrounding the grave .
Spokesman : Grave moved because first plot offered no room for other family plots . A medical examiner ruled Mary Kennedy died of asphyxiation due to hanging . Kennedy family members purchased some 50 plots surrounding the grave .