Assuming this is real, avoid the local pd. Contact your country's version of the FBI. Tell them you fear for your family's safety, there have been threats, and that organized crime might be involved. They can use ground penetrating radar to see if there's potentially any bodies under there before they even dig.
Anyone that hasn't read "It can't happen here" needs to go do so right now. While it was responding to the wave of fascism in America during the 1930's, it's remarkably prophetic about what we face now.