Iryna Zarutska's killer had 14 prior arrests. There are many examples of people having dozens of arrests for violence before they murder someone. There are dozens videos of people taking trash bags into stores and wiping them out because "It's less than $1k". People's cars are broken into and things are stolen (while the cars are occupied!) and the police don't even respond.

There's not some mystery about who is doing crime. They're arrested all the time and let go! If we simply prosecuted the people who are arrested crime would fall by 90% over night.