Can I sue for harassment/extortion in Maryland?

People with foreign accents call me day and night demanding money from me-they use different names and different agencies they claim to be representing. They have been doing this for about a year and a half. They say that me or my attorney needs to contact them immediately about a criminal fraud charge I'm facing over an unpaid debt (that I don't believe even exists). They have said they are the FBI, the Social Security Administration, the U.S. Legal Department and have also used various company names for which I can find NO evidence that exist. They tell me that I need to cooperate or I will be arrested by officers standing by outside my office waiting to take me to jail at their command. When I ask them who they are collecting for or who filed fraud charges against me since debt is not a criminal matter, they use obscene language and make threats to my safety and well being. I calmly tell them that if they validate the debt in writing I will be happy to pay it and they scream and hang up on me. They call me at home, at work, on my cell, and have harassed 3 of my family members on their home phone numbers in another state. They call me 10-30 times a day. I have been written up at work for excessive phone calls and I am on the verge of a nervous breakdown. This started in December of 2008. I notified the local police who basically told me to change my number (I can't change my work number and can't ask my family to change their numbers). I have filed reports with the FTC and the FBI as well and haven't gotten anywhere as of yet. They always call from different numbers but I know it is the same people because they read from a t6hreatening script until I start asking questions. My job and my sanity are at risk after a year and a half of this. I have 5 voicemails saved from them that they've left on my phone in the last week. If I can find these people can I sue them for harassment and extortion (threatening imprisonment in a non-criminal matter and endangering my job)? I'm at my wits end and these people have to be stopped. Thanks in advance.

Bud... What are you wasting your time posting on a board? You should be at your local State Police barracks filing a report. Based on what you posted, they will get the FBI involved, for phone record, and your deposition.