Javier Rojas is the kidnapper of Owen Farhidi, hired by Sam Farhidi to make his ex-wife Dana understand responsibility of a child.
Rojas was the boyfriend of the couple's nanny, Fabiana Caldera, so Sam conveniently paid him to kidnap Owen from school and demand a ransom. Rojas was arrested at the drop point, and as instructed, he lied and said Dana hired him.
Javier eventually cracked and revealed Sam was behind the frame job. As a result, his sentence was reduced, and Sam was arrested. (SVU: "Parents' Nightmare")