Yes, he is Dutch's brother.
Basically in issue 1 (I read the Predator Omnibus Vol 1, didn't know there were comics like these), Schaefer's brother and his partner find a gang killed Predator style in an apartment. One member survives and opens fire while running away. A Predator is in NYC hunting, this Predator later takes down a gang of corporate bosses (I guess) in the subway. Schaefer and his partner are told not by their Captain to not go further until General Phillips from the 1st movie comes in. He tells Dutch's brother about him and a little bit about the creatures.
Schaefer's brother goes back to the apartment where they found the gang. A Predator is there and they get into a fight. He knocks off the Predator's mask with a plank and the Predator sticks a homing device in him.
