actually murder rates have spiked dramatically since about the 70s
Even More so than you might think.
Remember, Trauma care is much better today.
IE people are surviving murderous assaults that they would not have survived 40 years ago.
If you are going to make a true comparison between 1970's Murder rates and today's, a correction to take account of this really needs to be applied.
It also occurs to me that the legal test for Murder should also be modified to take account of this too. many of todays "Murderers" are effectively getting away with lesser charges simply because their victims have good doctors. Neither justice nor the interests of public safety are served by this.