Adam Crapser was adopted from South Korea nearly four decades ago, but today he languishes in an immigration detention center in Washington State awaiting deportation because his American parents never filed citizenship paperwork for him.

Mr. Crapser, 41, built a life in Oregon, got married and raised children but will soon be forced to leave the country in which he has lived since he was 3 for South Korea, where he plans to eventually reunite with his biological mother in a small town three hours outside of Seoul, the capital. His family will remain in the United States temporarily, and they hope to reunite in South Korea.

“At this point I’m ready to just go back and try to make my life over there,” Mr. Crapser said on Monday night in a telephone interview from Tacoma Northwest Detention Center, a week after a judge denied his final request to stay in the United States. “There’s been some good things that came out of all this, surprisingly.”

Mr. Crapser’s sanguine attitude toward the wrenching dislocation that looms ahead is thanks in part to the media attention his case has attracted in both the United States and South Korea, he said. A South Korean documentary on his plight and the lives of other Korean adoptees led to his birth mother coming forward.