If you raise the issue, there may be repercussions, and there certainly wont be a reward.
Therefore, if you really want to raise the issue, do so anonymously:
- Get a one off gmail account.
- Gather anonymous evidence of coworker making up verifiable lies regarding kids, wife.
- Remove all metadata from any attached files/images.
- Stick to the facts, even if it means you have to let go some of the claims you want to make.
- Have a friend rewrite the email to remove "tells". Your personal style of writing will remove your anonymity.
- Never use the one off gmail account to send an email again. Do not read any response the business sends you to that one off gmail account. It's worth repeating: Do not read any response the business sends you to that one off gmail account.
He may just use false photos because he's obsessed with anonymity, so stick to the facts, and don't jump to conclusions like you did above ("He takes the time off to go home and play video games."). Don't include things you can't prove in an anonymous email. The stock photos on their own are sufficient to raise concerns.
Finally, who should you send it to? You do not know the whole story, so sending it to all his teammates or even the entire company will be inappropriate. I suggest sending the email to the following 3 people:
- Direct superior of coworker.
- Lowest level HR person who's responsible for coworker.
- Highest level HR person in the company.
If you want to use a minimal version:
I'm troubled by 'John Smith's use of stock photos which he shows around the office, falsely claiming they are actual images of his wife and children. It damages my ability to trust him, which impedes my ability to work with him. See attached images.
Sincerely, A concerned employee.