Others' immigration status: How can I find out what someone's immigration status is?

How can I find out what someone's immigration status is?

I know someone working outside of their H1-B limitations (50% certain), and hiring people who do not have a work authorization (100% certain). Normally I wouldn't care, but they are hurting my business.

I jsut want to let them that they're outside the legal limits.

[Law200]

Just call immigration and report it...

I don't want to cause problems for anyone so I would really like to avoid doing that.

What I want is to approach the guy and say, "hey, you're sponsored by company XYZ, so you know you can't be doing this. Please leave or I will report you."

Hopefully he'll get the hint.

You can try that as a first step. If he has an H1B he should not be engaging in other work activities. If that does not work you could involve the authorities if need be.

In order to give some weight to my allegations, I'd like to tell him that I know which company is sponsoring him, and therefore I know he is out of line.

[able1]

You can certainly do that.

Would you please be so kind as to tell me how I can check which company is sponsoring him, or what his status is generally? I am assuming it is not illegal to do that.