Here's how homicide rates compare in the 11 largest US cities with a Republican mayor and San Francisco (sorted by population):

  13.4 Jacksonville, FL
  12.6 Fort Worth, TX
   6.9 San Francisco, CA
  11.9 Oklahoma City, OK
  13.0 Fresno, CA
   4.9 Mesa, AZ
   6.6 Omaha, NE
   7.9 Colorado Springs, CO
   3.1 Virginia Beach, VI
  10.7 Miami, FL
  14.3 Tulsa, OK
  14.7 Bakersfield, CA

For comparison here are 14 cities with a Democrat mayor from the top 50. I picked these cities by taking the 11 Republican cities and for each picking the next highest and next lowest population Democrat cities:

   3.2 San Jose, CA
   8.2 Austin, TX
  22.4 Columbus, OH
  31.8 Washington, DC
   4.4 El Paso, TX
  17.1 Tucson, AZ
  10.9 Sacramento, CA
  30.7 Kansas City, MO
  32.0 Atlanta, GA
   5.5 Raleigh, NC
   8.1 Long Beach, CA
  30.9 Oakland, CA
  22.1 Minneapolis, MN
   5.8 Wichita, CA

What's your source? Where are you getting these statistics?

Parties of mayors [1]. Homicide rates [2].

[1] https://en.wikipedia.org/wiki/List_of_mayors_of_the_50_large...

[2] https://en.wikipedia.org/wiki/List_of_cities_by_homicide_rat...

VI is postal abbrev for Virgin Islands, not Virginia and Wichita is in Kansas.