What is the best way to find "proof" of where someone works.?

this person is a bus driver for the county of los angels (not sure what city), owes me money, is collecting welfare, and owes child support and yet no one can seem to get a handle on getting proof that she is working.
welfare frad simply asked her a few questions and left (what a joke huh).
i have the SS# and DOB and DL#.
i dont need addresses or personal phone #'s i already know all of that.
i need proof that this person is working.

If the person works for the county, you should be able to verify employment because it is public domain. Call the county HR office.

Why not call their employer and verify employment. Ask to speak to human resoruces and don't tell them anything about the situation.

If this person works as a bus driver then you can always take a pic of the person while performing her job.....and it would be perfectly legal since it's in public...

Follow her, as she drives her bus to work.
Don't use your car get a rental car to discreetly follow her and do your detective work. Good Luck.