Special Investigators Want To Meet With Me?

I’m freaked out and could use some advice. Two special investigators with the special investigations unit of my state’s Attorney General’s office showed up at my mom’s house looking for me yesterday. They told her I’m not in trouble, but that they need my help with an investigation. I figured I have nothing to hide, so I called to get it sorted out. When I spoke with one of them on the phone, his tone was very cold. He refused to tell me who or what they were investigating, and insisted I meet with them face to face. He also semi-accused me of not actually being me, and then promised he wouldn’t arrest me. My gut said he was lying, but to what end? It was so unnerving that I hired an attorney today, and scheduled a meeting with the investigators for tomorrow. It feels weird to have hired an attorney, but also seems like an appropriate time to protect myself. I keep wracking my brain for things I could possibly have done wrong. Am I overreacting? Any advice? Thanks.