On March 29, 2010, Law & Order is showing an episode called "Brazil".
When an environmental scientist, Dr. Oscar Silva, is poisoned during a global warming symposium, Detectives Cyrus Lupo and Kevin Bernard initially suspect competitors from Dr. Silva's field of study. It is soon discovered that Dr. Silva is involved in a messy custody battle with his wife’s ex-husband, Phillip Shoemaker and the focus of the investigation quickly shifts to the victim’s family. Meanwhile, the case becomes personal for Cutter as it stirs up unpleasant memories from his own past. Written by NBC Publicity
The previews indicate that the mother kidnapped the daughter and returned to Brazil and the American father has been trying to get the girl back. Note the stepfather is a "Silva".