Caller said they are from the federal investigation agency, calling in regards to litigation involving me. I called back asking questions about their organization, and they hung up on me. The person who left the voice mail and the woman I spoke to had a heavy Indian accent. Watch out for these scammers.

I also received a call from this "federal Inv agency".  They are very rude when i didn't give my full name and address.  To the point   They threatened legal action I I didn't make a payment by phone.   I refused and she hung up on me.  Very thick Indian accent, I p
Could not understand her name.  BEWARE.

These dicks target immigrants like my mother thinking that they'll fall for these scams even though she's an American citizen now who obviously knows better. I'm about to call back and give them a piece of my mind.

Calling them back, will only generate calls to your own phone number.

This is a scam.  Claims to be "Federal Investigation Department" which of course isn't an actual thing.  They claim to be investigating a lawsuit.  Similar to another scam that pretends to be the IRS informing you of an audit.  The IRS will notify of you of an audit via certified mail not over the phone.  Subpoenas are served in person, not over the phone.