Of course a career prosecutor would see a ‘crime problem’ as a result of insufficient prosecution.
Crime is complex, but largely related to poverty and economic opportunity. The interventions that are likely to matter most are so far outside this person’s perspective, that they are unable to see how modest judicial reform is merely the nearest corner of the iceberg.
You can look at https://en.wikipedia.org/wiki/List_of_United_States_cities_b..., sort by the homicide rate and almost all of the top 50 voted Democrat in the 2020 election. Not Tulsa or Oklahoma City, not Mobile. Eyeballing it, I don't see any other cities that voted Republican.
High homicide rates are a blue city thing, almost exclusively.
I'm happy to look at pre and post policy implementation compared with similar entities, taking national and regional trends into account. Anything else is posturing.
To me, this sounds like the precursor for a planned political career wherever he's moving to. Chicago is the icon for terrible awful no-good very bad liberal crime policies in popular conservative politics and an Illinois prosecutor who's moving because they just can't take it anymore would be optimally positioned to capitalize on that. Ah, politics.