Like I said, you're incorrect.
The densest population centers, regardless whether using an incorporated city, or an entire metropolitan area, are NOT, repeat NOT, even in the top ten of murders per 100k.
The worst areas for murder are moderately populated cities like baltimore, detroit, new orleans, etc...Around 6k people per sq mi seems to be the hotspot.
If it makes you feel better, a good portion of the lowest murder rate areas have D mayors.
While having a d mayor does not rule out having a low crime rate, it does correlate with the 12 highest murder rate cities. (stopped checking after 12. Number 10ish was no party affiliation, but that's neither r nor d)
https://en.wikipedia.org/wiki/List_of_United_States_cities_by_crime_rate
https://en.wikipedia.org/wiki/List_of_United_States_cities_by_population_density