Ok, I don't have any personal experience with this issue, but from the little I know most of the advice in the previous replies sounds pretty confusing and probably incorrect.
- there is not 'exit control' by the USCIS when you leave the US. Usually you turn in your I94 to the airline (which gets scanned or filed away), and that's it. If you have 'lost' you I94, the airline won't care.
- I don't know about your friends homecountry but: one of the main functions of my home countries consulate is to renew passports for their expatriates. He might want to go to his consulate, get a new passport (or in some cases an extension stamp).
- He will need a valid passport in order to travel towards his homecountry, mainly if he has to stop along the way. (his homecountry usually will accept him with an expired passport. It is not like he lost his citizenship or something.)
- He might need a transit visa if the plane lands in a third country on the way home. This is what the airline cares about, that they don't have to fly you back from e.g. Frankfurt or Amsterdam bc. you are not allowed to leave the plane there.
- Unless he is in removal proceedings, he is not required to tell USCIS, the consulate in his homecountry or anybody else for that matter that he is leaving.
Now some illegal advice from me :
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- If he leaves by air, he will leave a paper-trail. If he leaves by car or canoe, he won't leave a paper trail if he doesn't turn in his I94. If he never had a run-in with US immigration authorities while in the US (e.g. a 'notice to appear'), they don't even know he overstayed his visa. It is a well known fact, that the I94 system has gigantic holes with about 1/3 of I94s never beeing scanned in. This is the reason they want to start the US-VISIT system, to actually keep track of who leaves the country and who doesn't.
The reason I am bringing this up: If USCIS never finds out he overstayed, he might be able to re-enter on a visa as if nothing happened (it would require lying about your bio on the visa application....)
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