University policy covers this and in most cases an ethics review panel will be convened to review the complaint. The punishments vary based on the intent of the offenders, and whether the plagiarism was intentional or unintentional. Most plagiarism is unintentional like professor Nejati suggests.

But what, if the institutions totally neglect the written policies, i.e. instead of a maximum of two weeks of "initial evaluation" of plagiarism intend to pre-investigate the accusations forever, i.e. they do not even start, until the crime becomes too old to go to the police or state attorney? What, if the university takes three years to start the plagiarism process - and does not open some of the plagiarized master theses?

Perhaps mechanisms from the Open Science Framwork (OSF, https://osf.io) if more broadly used in science could help.  Those mechanisms (e.g., reporting on an open science website the  process  "lifecycle" of projects among collaborators (planning (which could include a planning document of rules and expectations for the collaboration -- a kind of informed contract), execution, reporting, archiving, etc. relevant to any project) that stays private and secure to the collaborative group. It could then be available to access by the members of the team to better avoid and respond to conflicts of this sort among collaborators (that could be more readily accessed by university committees; or external evaluation committees in the event there is post-university level continuing disputes)  and also (possibly) where there may be inter-team disputes about precedence of and substantive contributions to research (all historically documented) on such an open science platform.  Openness and transparency may be among our best mechanisms going forward for reducing conflicts of this sort.

Well, after a few years - and after the legal three years appeared to me over - I put dozens of files together and mailed alltogether to the state attorney in the same city the university is located... after some time the state attorney wanted to know exactly the "date" and "time" the accused crimes had happened... what a stupid question from the state attorney - all this was very clear from the proofs; but I have to consider that many if not most of the state attorneys also studied at the same university they should start a criminal investigation against... and they are known to even warn people (like a terrorists' son) just before a house search to hide their potentially illegal wapons... so, it looks like there is no legal way to fight the plagiarism supporting university in any way.

Thank you for reading and, perhaps, some understanding. I really tried to get a copy of a so-called "Diplomarbeit" (comparable to master thesis) from the responsible secretary - but the work was not there at the first time (it was finished but not yet stored at the final place), and at the second time I stopped by, the secretary found and showed me the bound work out of the key-locked shelf, but I was only allowed to read the title - and then was informed that I was not allowed to read or even copy the work, since this belonged to the university (which I can confirm appears to be totally correct since the "Diplomarbeit" is officially a supervised work which may (and should) contain ideas from the university - in contrast to a PhD thesis which should be "independent" work, therefore those data then belong to the doctorate scientist (alone) and should be accessible to the public). So I do not really know (yet) if my idea for the project was anyhow acknowledged in that (and later) "Diplomarbeiten", but since none of my pioniering work for the lab was ever officially acknowledged there is reasonable chance that my work was also not acknowledged... interestingly, the student was not allowed to continue my work in her PhD thesis although I was told she wanted to continue on that work (so at least she acknowledged showed a real interest in the field I pioniered - and there usually are not many women at all in physics). It looks to me she is now trying since a decade to get a PhD somewhere else, in a very, very different field - and probably extremely or even more challenging, which gets my full respect to try such a challenging other field.

Well, the first and most plagiarizing students knew all the relevant parts about my original work - although some of them tried to lie exactly in the way you described (that they never heard about me). This was really funny, since two students felt to be in a competition against each other: one was on the mouse project on VLA4/VCAM1/SDF1 and lymphocyte-like cells, the other on the human project on VLA4/VCAM1/SDF1. The one on the mouse project mentioned her view to me that I am in the good position as the inventor of such projects to be on both projects, and that her competitor on the human project could be faster since she was about one year ahead in her study of physics (not on the project).... One of the biggest lies in that plagiarizing lab is to allow the best grades for clearly questionable work - but Bavaria is known to have provided the biggest plagiator in Germany, also the very rare and very best grade for his thesis (Ex-Dr. von und zu Guttenberg !, who only after long accusations of plagiarism had to step back as minister of defense... interestingly his family had spend a million Euro to a university hospital around the time he was allowed to start a thesis... well, although this was just a co-incidence, in general, corruption in Bavaria has a long tradition...