Board Thread:Spoilers!/@comment-1916997-20180303031455/@comment-1916997-20180303150228

In this interview it states the killer is revealed earlier than you would think:

https://www.hollywoodreporter.com/live-feed/once-a-time-sets-up-killer-arc-series-finale-1090086

I think that still supports Jack being the killer, because they might show Nick killing someone in like 714/715, and explain the why in 716's FB.