How do I go about helping my husband find his adopted daughter?

Haley • Mommy to two amazing babies❤

9 years ago, before my husband and I got together, he was with a girl, in Michigan, and they were forced to separate and supposedly she was pregnant, had their baby girl, and gave her up for adoption, she is just now telling him, he's curious about his daughter, and she is refusing to give him any information, I just want to help him find her, or find out if she is lying. Anybody have any tips?