It does not matter what text book definitions of Communist and "Democratic Socialist" are. In today's USA what the left want make them functionally identical, there really is no rational debate on that.
It is interesting that you have not heard anything about the FBI investigating his wife. Just goes to show the criminally biased media in our country. However, if you do a simple google search there is info available.
http://www.cnbc.com/2017/05/12/fbi-probe-could-kill-bernies-progressive-power-commentary.html