What's the noun for releasor? Here's the word you're looking for.
release
The event of setting (someone or something) free (e.g. hostages, slaves, prisoners, caged animals, hooked or stuck mechanisms).
(software) The distribution of an initial or new and upgraded version of a computer software product; the distribution can be either public or private.
Anything recently released or made available (as for sale).
That which is released, untied or let go.
(biochemistry) The process by which a chemical substance is set free.
“In Peterson, the DOC records were being introduced to establish the defendant's prison releasee reoffender status at sentencing.”
“Reenacts section 2 of chapter 99-188 which makes clarifying changes to the prison releasee reoffender statute and creates enhanced penalties for repeat sexual batterers.”
“That is, people who are homeless are at risk of ending up in prison, and the prison experience itself places many releasees in jeopardy of becoming homeless.”
“They are now involved in further studies to extend their work beyond first-time arrestees to a large sample of prison releasees.”
“The court observed that in this case there was no mention of full satisfaction for the Berrios' injuries in the Release, only a release of claims against the named releasees.”