Why would a murder investigation be halted in DC?

In order to answer that question, you may need to consult with some basic civics.  Washington DC is actually under the jurisdiction of the Congress.  Congress in turn, has delegated governance to the locals.  However, it is still under jurisdiction of Congress.

So, that raises some interesting questions.  For example, why would the murder of Seth Rich not be fully investigated?  Why would the investigation be halted?  How can this be explained?

This may strike some people as tin foil hat kind of stuff, but I don't care.  Just open your eyes a bit, and see for yourself.  Poll after poll says that there's something wrong with the track the country is on, and why not look at something like this?  Could there actually be a conspiracy to silence any attempt to get to the bottom of this murder?  Why would Congress not intervene if there was something fishy going on in their own town?  After all, it is Congress' town.  The US Constitution has empowered Congress to run it.  If something is wrong, why don't they clean it up?

Now ask yourself this question:  if they won't clean it up, is it perhaps because it would not serve their interests to do so?  Is there any rule of law in Washington DC?

To put this another way, we could have an organized crime mentality in DC.  If someone steps out of line, they will be whacked.  Then to explain why this murder isn't being investigated, one has to accept the possibility that this situation is now the reality in Washington DC.  If so, the rest of the country has got to clean it up, because they won't, or can't.