This is an "in theory" question, right? I can't bring to mind any examples of any criminal act being legalized and hordes of prisoners being released on the streets. My response would be: If it was unlawful at the time it was committed - and the defendant was convicted of the unlawful act under the then-lawful statutes, then he DID the crime and should serve his sentence.
kidnap
Murder
He is taken prisoner
The accused, or the defendant.
If a prisoner is being prosecuted for another crime and the charge is still pending then the prosecutor can file a detainer with the location where the prisoner is confined. This ensures the prisoner will not be released back to the street without first answering for the other crime. The prosecutor can writ the prisoner to their location prior to their release from prison to try to dispose of the case or the prisoner can be taken into custody when released on parole.
Grand theft.
I belive so.
He or she would be charged with the crime and tried, just as he/she would otherwise.
Hate Crime
It depends on the type of crime and how long they are in prison for.
The term for when a prisoner repeatedly commits a crime is "recidivism." Recidivism refers to the tendency of previously incarcerated individuals to relapse into criminal behavior after serving their sentences. It highlights the challenges of rehabilitation and reintegration into society.
Utopia.