State Investigation Department Eric Matthews Warrant threat District of Columbia Nationwide

I received a cal tday from a "genteman" named Eric Matthews claiming to be from the State Investigation Department, I did not receive the call as I was busy but when I checked my voicemail, the person on the ther hand sounded quiet professional and tld me to call him back at the number 202-239-0433. He claimed I was under federal investigation (did not mention on what grounds), atfirst I was a bit shook but then when I got my neves back and started some online searching I found this same number was used to claim that they were from IRS and threatened another person. I really don't know what to say, when I investigated further I found this website and a little fact that the number was a sprint cell phone. I'm not n expert but I'm pretty sure that official phone cals of such nature are not made on cellphones.