The kidnapper in I Will Find You appears to be Hayden , played by Milo Ventimiglia , according to a recap of the show’s twist ending.

Quick Scoop

The series builds toward a late reveal, and the final turn points to Hayden as the person behind the abduction.

That said, some coverage frames this as a twist ending rather than an officially simple “case closed” answer, so if you want the exact episode-by- episode breakdown, I can give that too.