I recall a segment about a man who had divorced his wife. I can't recall if it was a custody exchange or how it went down, but the ex-wife joined a religious cult/movement group type thing, and took their son with her. He was searching for the son. I don't recall the son's name, just that he was school age, I would say he was under 10 years old.

Please help me recall who this is! If I remember correctly, the segment was solved.

Is it Patt Farmer (http://unsolvedmysteries.wikia.com/wiki/Pat_Farmer) who kidnapped her grandson and accused her mother, stepfather, and father of being satanists?

I recall a segment about a man who had divorced his wife. I can't recall if it was a custody exchange or how it went down, but the ex-wife joined a religious cult/movement group type thing, and took their son with her. He was searching for the son. I don't recall the son's name, just that he was school age, I would say he was under 10 years old.

Please help me recall who this is! If I remember correctly, the segment was solved.

That sounds like Nicholas Karopoulos (https://unsolvedmysteries.wikia.com/wiki/Nicholas_Karopoulos). He was abducted by his mother Levia, who was part of a cult. His father Arthur tracked the cult to various locations but was unable to find his son. Thanks to the broadcast, Nicholas was found and reunited with his father.