@LostWanderer: I am in agreement with the accepted answer. The purpose of education is to learn. The purpose of assessment is to measure the degree of learning. Anything that undermines the integrity of the assessment is academic misconduct. For a more thorough discussion of the purpose of grades, see this: academia.stackexchange.com/a/31448/16183

If the student was not warned or did not see a warning not to reveal the exam to his fellow students, and, as it seems, was aware that the exam is the same, then clearly, they are trying to push the boundaries of what is acceptable. Yes, this is misconduct; in fact, a particularly nasty case, when care is taken to accommodate their special requirements; it is abuse of goodwill, essentially. Now, the exam conflict is not of the student's making, but it should be obvious that they should cooperate in keeping the assessment procedure fair.

"nothing explicitly stated" - it is difficult to prove that the student did or did not know whether the exam was the same. Intentionality matters - here, as everywhere. The speed at which the student exchanged information weakens the case that they are making that they were unaware.

Regarding the "Why not?": It is extremely easy to create fake screenshots of Twitter/Facebook/Whatever feed or messages. Every major browser includes developer tools to alter the contents of a page, so if I have issues with the OP's peer I could easily (i.e. in literally 2 minutes) exploit the situation and craft a fake screenshots that looks 100% legit and make that guy pay for whatever the issue was. The only knowledge required is minimal HTML (just to understand how to change the text) and where you can edit the page contents.

@Bakuriu: In any case, there is a very simple way for a board to find out whether the screenshot is accurate: ask the student. Are you suggesting she should lie, or refuse to answer?

Do you take in account that being "obnoxiously defensive and argumentative" can happen for the simple reason that the student is actually innocent and honest and simply cannot ascertain how convincing the wrong accusations are looking against him ?

@LostWanderer I have been involved in relevant investigations, and in most of these, evidence is not a one-shot, but accumulates. If a student has an exam in the morning and hurries to show the exam to his fellows before they have theirs (presumably they already revised before that day, so what is there to gain from looking at yet another variant of an exam?), it is not conclusive, just additive evidence that the student may have thought that they would profit from seeing that particular exam. In isolation, this is insufficient to judge intention, but in context it adds evidence.

Sorry, but this doesn't make much sense. Those exams were on different times, so it is natural to expect they have to be different, unless told otherwise. When I was in university we routinely talked about exams with fellow students who would do them the following week, the following semester or even the following year. After an exam is finished you can talk about it, you are not signing a NDA lasting forever. If a teacher doesn't bother changing the exam contents after each week, semester, or whatnot then it's their problem (I had a couple of teachers like that).

@CaptainEmacs I wouldn't necessarily say that rushing to share results is any indicator of guilt. People absolutely study the last day and one of the best ways to study is practice exams. Not saying the student isn't in the wrong but I would guess it is an honest mistake instead of willful cheating. Most students I know would assume a test taken at different times would be different.

I agree with Andrea completely. It would never have even occurred to me that the tests would be the same. Plus when I was in school, I was encouraged to get old tests to better prepare for exams. And getting feedback from students that had already taken the course was not considered cheating. It was considered taking the initiative to be well-prepared.

@AndreaLazzarotto: in maths, for example, a different examination often consists in changing numerical values in problems. So, talking about the examination would give some information to other students: the type of problems, the balance between theory and concrete problems,... if you give completely different examination, it would be unfair too.

I agree: Even with different Exams, if he gave details of the exam he took to some students, they will have an unfair advantage, since this information is not available to all students. - And the intention was clear cut, they wanted to get an unfair advantage by getting "inside" information (no matter if it was a similar or actually the same exam) - and this is academical misconduct.

@Taladris so what? The type of problems should be well known in advance (an exam is based on the course syllabus, or it should be) and it should be similar for each exam. Studying computer science I had several math related exams and in all cases we were provided with copies of the previous exams as convenient PDF downloads.

@gtwebb I said that it is not definitive, but that it adds to evidence. Frankly, if all the past exams available have been revised by the students, why would it be so important to share this very latest exemplary if not for the reason that it provides important clues not available in the others? Even if it's just an exam in a similar style to that in the afternoon, it provides an unfair advantage and a skewing of scales. It did not occur to the student to ask whether he could share the exam, either. And that, again, is per se not conclusive, but cumulative evidence in the present context.

@LostWanderer "I'm just trying to make sense of this situation as it seems to be really tricky." It really isn't. Also, "It wasn't explicitly stated!", "Maybe Facebook hacking!", "How were they to know!?" doesn't add up to a line of compelling reasoning to point to the student not cheating. It looks for all the world like someone desperately throwing up every argument they find and hoping one sticks. If a student in my classes approached the problem like this, they'd very swiftly move my sympathies from "Honest mistake, level a meaningful but recoverable penalty" to something much more severe.

@AndreaLazzarotto You would expect a professor to make a whole new exam on the spot for a single student who had a conflict? It's one thing if it's two different classes of the same course that it was known from the beginning of the semester that multiple exam times would be needed. It is entirely different if a professor helps out one student by providing an alternate time the day of.

@LostWanderer The primary problem is that, to quote Chicago, "I didn't do it, but if I done it how could you tell me that I was wrong" doesn't seem like establishing innocence or ignorance. Yes, Facebook messages can be faked - but unless she's arguing that she didn't do any of those things, that's irrelevant.

@pwcnorthrop yes, because ensuring the student doesn't speak with fellow students is impossible. Actually the odd thing is that this student got a special time just for him/her. They could have waited the next exam date.