I've lived in this area for almost my entire life - a long time. You are absolutely correct about the longtime policy of LEO coverups in this area. Many of the Capitol Hill political elite, including politicians, lobbyists, etc., are mainly transients who really don't care what happens to the regular Americans who live around here. Therefore, the ruling class here wants all those who live here temporarily to "feel safe" and not be "alarmed" by the truth regarding the serial killers, rapists and other criminals who enjoy Rock Creek Park along with all those temporary residents with a false sense of security.
Rock Creek Park has always been the favorite haunt of homosexuals trolling for tricks, serial or opportunistic rapists, and other dirtbag criminals who find the yuppie, liberals who use it to be easy marks to prey on. And in those rare instances where a perp is actually captured, tried and convicted (about 1% of all crimes committed), the local criminal justice system quickly releases them back into the communities from whence they came - to breed and perpetrate more crimes once again.
Just doing the math, the odds are overwhelmingly in favor of this being a suicide. That's a pretty boring ending though, a lot of people will reject that just because it's just too dull. Still, Conduit must be such a jerk that she found enough motivation to punish him by offing herself. Her plan worked amazingly well.