What to do (years later) with otherwise good student who has accidentally plagiarised part of PhD thesis? Here's a not so hypothetical situation. International student x is very talented but comes from a background where technical writing is not taught or understood very well. She writes a great thesis with a good literature review and nice results. However, the results are based on two key papers from previous students in the group. She decides to give credit to the papers in a special chapter, which she starts by saying "I need to give credit to this and that paper" and proceeds with copying paragraphs wholesale to describe what those other students did. 

This was a few years back; X is now faculty at a good school and she contacts me (past advisor) in teary-terrified voice to let me know that she plagiarized in her thesis. I am now in a panic as well. How could I miss those? And how could she do that?? We both risk losing our jobs, and she is at risk of losing her degree as well (which, by the way, was a very strong thesis with a good number of top journal publications). 

As far as I know there's no process for revising a thesis after it's been submitted and I don't know what else to do short of turning ourselves in - which I feel morally obligated to do.

Please advise. 

Edit 
Thanks all for weighing in on this. I spent the night going through the thesis and there appear to be three more sources that are suspect of being plagiarized, all in the same wretched chapter; one is a thesis of a colleague, the other is a textbook and the third is a book I wrote a while back. So this is more serious than I thought. 

She has unfortunately not used quotes for the material, i.e., instead of saying "[paper i] says ," she just went on with "[paper i] says this and that."

She has not been accused of plagiarism by anybody. I am guessing that she has finally come to grips with good writing standards and upon looking through her thesis she realized that her "summary" was actually plagiarism. I have every reason to believe that she did what she did in good faith (she has proven her honesty on many occasions).
Did any of the plagiarized material make it into journal papers, or was it all literature review that was never published outside of the thesis?

If some of it made it into papers, then it's important to contact the journals and publish corrections.  This is more straightforward and predictable than dealing with the thesis itself.  If the plagiarism is confined to background material, then I don't think retracting the papers would be necessary.  Instead, I expect it would be possible to publish a correction that indicates the plagiarized portions and provides citations.  This would be embarrassing and would hurt her reputation a little, but it would solve the problem as far as the papers were concerned.  It would also strengthen the student's case for dealing with the thesis if she can say she voluntarily corrected the publications and did not need to retract any of them.

If none of the plagiarized material was published elsewhere, then it's trickier.  Once all the original results are published in research papers, I doubt anyone will read the thesis and discover the plagiarism.  Even if they do, they might take pity on the student and ignore the plagiarism.  (I once ignored some mild plagiarism of my writing in the background sections of a thesis at another university.  The student had already graduated, and I found no evidence of plagiarism in any of his research papers.  If I knew for sure he could just file a correction to the thesis, then that would make sense, but I wouldn't want to potentially destroy his career over this mistake.)  So she might well get away with it if she doesn't say anything.  Still, I'd advise her to officially confess to the university.  Turning herself in is likely to lead to a much better outcome than being caught by someone else.  Plus it's the right thing to do, and it will save her from years of worrying about getting caught.


  We both risk losing our jobs, and she is at risk of losing her degree as well (which, by the way, was a very strong thesis with a good number of top journal publications). 


Unless your university is extraordinarily strict, I don't think your job is in jeopardy.  On the other hand, the student's degree or job might be, depending on how the university handles the situation.  Based on your description, I think it would be unfair for her career to be ruined, but I can't predict what will actually happen.  I hope your administration's sense of fairness is the same as mine, in which case a correction will suffice.

The hardest situation will be if she decides to remain silent.  In that case you probably have an obligation to turn her in, and it would look terrible if anyone found out that you knew but didn't say anything.  On the other hand, turning her in would be a tough decision.  Much better for her to turn herself in voluntarily.