Abit about my background first: I'm currently undertaking a PhD but have previously worked in healthcare for around 4-5 years. During this time I developed a suite of code to produce results from clinical sequencing data (a NGS pipeline plus filtering steps).
Recently while looking for example PhD theses to use as the basis for my own write up I came across a recent PhD thesis that contained a reference to a github account, which contained code I had written.
The code in the repo is over 97% direct copy of code that I had produced while working in my previous employment - the remaining 3% appears to be a cut and paste of lines from my original pipeline into a popular pipeline management system.
edit I should note here that this remaining 3% had previously been submitted by another ex-colleague as part of an external qualification - for which I was the internal assessor, this person claimed sole authorship at the time.
edit I should have noted that development of this code started a year before entering the employment that I mentioned, as part of a postgraduate qualification that I completed, submitted ironically - along with prototypes of the discussed code - to the same university. Just to clarify the IP issue, the university in question assigns ownership to the student in these cases.
There is no direct reference to my own Github repo which contains the original code (with GNU public license) and no acknowledgment of my authorship (I am mentioned indirectly as a maintainer of the code elsewhere in the thesis). I had no knowledge that the author of thesis was using my code as part of their thesis.
The author of the thesis was in the same department as me, however was at no point involved in the development of the code while I was present. They have since submitted and passed their PhD and are now employed as a PostDoc in the same department.
I can show continuous development of the code over a period of 4 years previously via my Github logs. The author of the thesis has only a single commit and no history in the github logs.
The person in question has essentially written a PhD chapter based on analysis of sequencing data that I did. The code is just part of the story, since the person also claimed that in addition to writing the code they used the code to produce the results in that chapter. They didn't - since I know that I ran the batches in question (this was around 2 years of work).
What steps should I take (if any)!