Denver was a sanctuary city for a very long time. It isn't what caused Denver's mess. It is holding back on criminal prosecutions (regardless of reason).
Whether you like it or not, if you disregard the law in favor of poor policy and let folks disregard the rules, you wind up with a higher crime rate than you had before you started letting folks get away with crime.
It isn't even difficult to figure it out. Any logic student would be able to see the link.
Soros has done this intentionally with his investments in DA's in key cities and States. It is easy to follow the pattern of destruction he has caused. Democrats destroy everything they touch. When cornered, they screech for more money.