It would be different if the photographer was using a timer, remote, or other sensor to take photographs of the monkey. In those cases the photographer would clearly be in control of the situation and the copyright.
This seems a little different in that the camera was stolen from it's owner and pictures were taken. Right now the U.S. courts don't view monkeys as people (http://www.cnn.com/2013/12/09/us/new-york-chimps-personhood/), but what would happen if the monkey was someone's pet? Who owns the copyright on a picture taken from a stolen camera?
This seems a little different in that the camera was stolen from it's owner and pictures were taken. Right now the U.S. courts don't view monkeys as people (http://www.cnn.com/2013/12/09/us/new-york-chimps-personhood/), but what would happen if the monkey was someone's pet? Who owns the copyright on a picture taken from a stolen camera?