Prosecutors should be fully liable for illegal actions they take even when they're performing official duties. This guy should be serving a sentence years long, not days.
This is where every system that polices others plus themselves falls down. You can think of qualified immunity as professional courtesy between lawyers.
In Wisconsin the Republican legislature and Republican governor (the recently failed presidential candidate Walker) passed and signed a law limiting political corruption investigations, because they were annoyed at all the investigations and convictions of themselves.
No one watches the watchers.