In the mid-1990s, journalists and human rights groups began to uncover a web of slave labor linked to some of Brazil’s biggest export industries: cattle, soy, sugar cane, and pig iron used in making steel for automobiles.

The Brazilian government responded, setting up rapid-response teams to find and liberate victims of forced labor. Since 2000, more than 30,000 slaves have been freed.

Leandro Carvalho had a comfortable job as an insurance agent on Rio de Janeiro’s Copacabana Beach when he decided to join the force. And he says he doesn’t want to quit until the last slave is freed.