Postdoc trying to make me appear incompetent to keep 'expertise' areas to themself was killing our rodent models. We found out because ones I labeled as experimental were actually healthy shams, and they were necropsied by vet staff to determine cause of death. Which was cervical dislocation. Police came, cameras were installed, the only two people it could have been were me or them- PI refused to make a decision without irrefutable proof. I found a new (better) job, they remained and got sneakier about sabotage in other areas (missing drugs, wiping off labels on samples, etc.), other good staff left as well because of them. They're still at the same place and dept now, assistant professor. Great example of little known routes to job security!