I suspect someone deliberately ruined my experiments by poisoning my lab insects. What should I do? I'm a graduate student who's currently working on an experiment involving some animals. I have two separate places where I keep my animals, and one of them is in a locked section of a lab (which is only accessible by myself, my PI, and a few other investigators).
A few weeks ago when I came into the lab, I noticed that all of the animals in that locked section had died. Without going into too much detail, after a quick investigation I found that a gas valve must have been opened to kill the animals, and then closed again. It is impossible for the valve to open spontaneously, let alone open and close. I also determined that it couldn't have been a gas leak because I have a habit of always setting the valve to a certain position after closing it, and it wasn't exactly in that position when I checked it, so it must have been physically moved.
I thought that maybe the stars unfortunately aligned and I had gone wrong somewhere for this to occur, so I left it alone and kept it to myself but have been careful to check the valve everyday afterward.
A few days ago, the animals were dead once again. The valve had also been moved. Although I don't have concrete evidence, I'm strongly suspecting that either my PI (who I don't have the best relationship with) or another investigator in the lab is deliberately killing the animals. I don't know what to do now, who to approach, and what to say. My entire experiment is now also in jeopardy. What steps do I take?
Clarifications / responses to comments:

The &quot;animals&quot; are insects, so &quot;animal care regulations&quot; are limited
No one has commented on the deaths. My section of the lab is rarely used, so they may not have noticed.
There are no security cameras.
I assume you're doing CO2, in which case you frame it as a serious safety concern and insist on looking into it. You're in an enclosed space with an asphyxiant that appears to be leaking. This is a critical health and safety issue and should be treated accordingly.
It's unlikely in my opinion that you are being sabotaged but if you are whoever is doing it will stop if these issues are investigated