for sys/net admins is to keep in the back of your mind that your actions can be scrutinized somewhere down the line, even if you are the most conscientious, morally upright employee.
If you work in an environment where you are the key technical resource, and others don't have the chops to safely manage the systems you designed/built, you still need to be sure that you put mechanisms in place to track access first, and then you need to provide equivalent access as agreed with management, to other administrators. Since you have the tracking mechanisms there, you can unravel who did what if there is an issue.
I know that it's hard to do this if you work in a hostile environment, or one where people are defensive about their jobs. This is especially true if you are the lead or only techie with the skillset to safely operate in the environment. But without being too paranoid about it, try to inform management as to what you're doing occassionally, track access of yourself & others (if you exclude yourself by using other means of authentication or access, you won't have a leg to stand on, since your actions weren't logged and you could have 'hidden' them).
Try to foster a trust environment with your peers, help them along in becoming competent while giving them access appropriate to their skillset (but make sure others know they are accountable for their actions), and you would improve your chances at exonerating yourself if the PHB's ever start pointing the accusing finger at you.