Is AUTHOR wrong in the post ? POST : Alright, backstory time. 

I'm in a high level Biology class at uni with a lecture and lab component. The class is Comparative Vertebrate Anatomy and labs involve looking at a lot of different kinds of specimens to identify structures, doing dissections, etc. The professor really only has two ground rules in lab: 1) Don't leave your scalpel out where it can cut yourself or someone, and 2) Don't use any sort of writing implement as a pointer on specimens so as not to accidentally mark on them since it can be hard to remove marks from some specimens. The prof has made these two rules thoroughly clear from day one as the only thing he'll really get mad at if he sees you doing it. I've noticed almost from the get go a student who consistently either forgets this rule or just doesn't care. AFAIK he hasn't be outright caught yet, but I had no intention of calling him out directly and snitching to the prof. I'm going to call him the Scribbler 

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Fast forward to a recent class, we're doing a review day on skeletal anatomy. I prompted the professor to come over with a question about some structures in the lab manual but realized we don't have that particular specimen at the table so I went to the table where the Scribbler sits and asked the group if I could borrow said specimen, to which they obliged. On coming over with the specimen and asking my question, the professor noticed mild marker line across the specimen and it was clear to him it wasn't my doing since I just brought it over. He asked me where I got the specimen from, and I wasn't really thinking about it because I was focused on the material, so I just pointed to the table where I sourced it. Now I didn't realize it, but no one else at the table was using a marker except the Scribbler. The Prof immediately went over and asked Scribbler if he was responsible. Scribbler goes on to categorically deny the accusation, but I guess the lab assistant had seen Scribbler do this in the past and the professor wasn't buying the feint. He chided the student, and returned to me and class resumed as normal. 

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Lo and behold, after class, the Scribbler accused me of intentionally ratting him out to the professor, which makes no sense because I have literally no impetus or motive to do so, and I made that clear. I learned that it cost him 5 points from the daily lab grade (out of like, 30?) and he has to come in on a separate occasion to go through all the specimens and any specimens with marker on them. I explained what happened but he went on to call me an asshole and say that even telling the professor I got the skull from their table was a dickish move. I sorta folded and apologized and went on my way to avoid making a situation out of things. 

tl;dr: I accidentally outed a classmate of mine to the professor for violating one of the few ground rules of our lab class and he got scolded/a point deduction and has to come in and clean a bunch of specimens (potentially, not sure how many he's marked up). 

So, y'all, AITA here? I felt sorta bad about him having to clean all the specimens, but frankly, it isn't really that hard of a rule to follow. 

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