How to restore trust in a toxic lab environment? A friend of mine started working in a biology research lab where several research groups share space and lab equipment.

Recently the environment has become quite toxic as the people started to mistrust each other.

It started with people not talking to each other and instead preferring to email everyone about "How to use Equipment X". Then later "To the person who used Equipment Y before me, please ask your supervisors how to use it properly". Now everyone watches each other to guard the equipment. In spite of this chemicals and samples started to disappear from the stock and tools get contaminated over night. 

As my friend is "the new guy" he is often the target of accusations. 
His colleagues from his research group are trying to protect him but still something needs to be done. 

Now what to do? How to get back the trust? Should the institute heads get involved?
Institute heads seems like overkill at this point.  How about the group leaders for starters?

Your friend might find it helpful to schedule his lab time when his groupmates will be present.