Intellectual theft by a colleague, how to respond? A recent exciting but unpublished discovery of mine was scooped by a colleague. I am a PhD student and I shared the discovery with the colleague a year ago. The colleague is a professor who came from the research group I work in. I found out about the scoop through my adviser who attended the colleague's talk about the discovery; the colleague's group did similar research that led them to the same discovery after we talked. 

Obviously my adviser and I were surprised, upset, and angry. Initially after my adviser confronted the colleague about this the colleague was argumentative but eventually saw the light and became apologetic. The colleague offered to retract the paper that was accepted for publication but not published until we've published our findings (it's taken so long to publish for good reasons). However, the colleague is still pushy about trying to get at least something from their research out, but it is our judgement that any of their results would scoop my discovery.

Although I haven't talked with the colleague since this happened (my adviser has been mediating), I get the impression that the colleague did this intentionally with the hopes that it would go unnoticed by us.

So my question is this: what should I do to ensure this colleague receives their comeuppance i.e., does this deserve some sort of punitive action on my part? I haven't asked my adviser yet and any suggestions I receive here will certainly be discussed with my adviser.
It sounds like your adviser is already on the case -- let her handle it. She may know the colleague better, may know better how to handle such situations, and is in a position where she may not care about consequences any more if she calls out the colleague about the issue (because she already is a professor). You, on the other hand, do not have this luxury and consequently would be better off letting someone else handle this as long as you think that it is handled in a way that goes in the right direction.

So, rather than being involved yourself, let her handle that and keep you updated as to what is happening.