At the fore stands Manuel Elkin Patarroyo. The aft contains his research subjects—30 individually bagged owl monkeys, each no bigger than a small housecat. The captain guides the boat toward the bank.

The saga started in April 2011 when Colombian conservationist group Entropika, led by Angela Maldonado, filed a lawsuit against Manuel Elkin Patarroyo, an immunologist who founded the centre. Among ...