Quickly Collect Your Evidence!
--contain false allegations about you (personally and/or professionally);
--contain new/surprise allegations that differ from previous allegations being made against you;
--promise certain actions/next steps to deal with your issues;
--inform you that there will or won't be an investigation into any complaints you've made;
--contain offensive and/or hostile language and/or threats against your job;
--provide any sort of evidence--no matter how small--that supports your complaint;
--contain your written description of issues, requests for clarification, explainations of incidents at work, etc.
Anytime you get important information in writing, you've got to get hard copies made and electronic copies saved to ensure that you will not lose your evidence/proof.
My former employer made all sorts of surprise and wild claims about me on my year-end performance review. As I sat in the meeting, I shot holes through everything they wrote and shot holes in their verbal defense of those written comments. Sensing that I had bested them, the HR representative raced to her office and made a number of changes to that performance evaluation. She deleted many of the wild accusations and softened the other accusations that were being made against me.
My employer had a process set up where reviews were posted on the company intranet prior to the meeting. So, everything discussed was out there for me to access, print, save, etc. 10 minutes after that review meeting, my evaluation was modified to look less retaliatory and to delete some of the worst false allegations being made against me!
The problem was, I raced to my office and made 10 copies of my original review, I emailed it to myself, and I saved it to disk. So, I wouldn't have to worry about losing my proof that my employer was going to great lengths to create a hostile environment for me and that they had no issues with lies and exaggerations of fact.
Had I waited, I would not have had any proof of the accusations being made because 10minutes later the review was changed. I would only have had the watered down review, which my employer could have argued wasn't retaliatory or offensive.
In the case of a friend (I was her primary witness at work), our employer would have people go through both of our computers and desks looking for evidence in her complaint against the company. Our chairs would be moved, the mouse of our computers would be in different locations from where we left them, our computers would be on or our computers would be on screens we didn't normally access, etc.
Don't think your employer won't rifle through your desk for any clue about information/evidence you're compiling and don't think they won't go in and read your emails and other documents. My coworker had files disappear from her computer and there was a sudden need for her department to "clean up" their electronic filing system and move files to a central location.
If you get anything relevant to your complaint, make sure to preserve your evidence. In this age of technology, it's still important to maintain a hard copy of evidence in case your electronic files become corrupt, you lose a disk, CD-Rom or flash drive, etc.
You will need to present a complete batch of evidence to any investigator or lawyer, so be sure that you maintain important records of what's happening at work and the personal and professional impact you're experiencing (hostile behavior, increased surveillance, health issues/excessive leave taken at work due to stress of harassment and abuse, etc.)
You must document everything. But, you must also maintain a copy of everything. Getting things in writing--once--isn't enough. If you move, lose a file, etc. you will not have any proof of wrongdoing. Keep multiple copies of important documents and save them in several places.