When you load a prisoner into a transport pod and send them to another colony, they are no longer a prisoner upon arriving. You have to recapture them, or in the case of the guy who I podded in front of my prison in my main colony, they get immediately gunned down by turrets upon arriving and die.
Can confirm, used a transport pod to send a prisoner from my caravan after it defeated an outpost and the prisoner was hostile and got gunned down when he landed in my colony.
This is the case even if prisoners are podded with a colonist escort.
Duplicate of https://ludeon.com/forums/index.php?topic=46175.msg438995#msg438995 - has been fixed.
Thanks for reporting! ;)