Once you get his message, return to Copeland’s Camp and talk to Copeland to start this mission. Head to the small camp south of the Horse Lake NERO Checkpoint.
The Camp is situated on top of a rocky hill but its possible to sneak in from the western side of the camp by climbing the rocky ledges. However, you have to be careful of the hidden bear trap in the bushes. Make sure to disarm it and relocate it if you want.
Climbing these ledges will take you directly under the tree Camp. From there, you can climb up and find the target there. kill him immediately, get the proof of kill from his body, then get rid of his allies from an easily defensible position. You can also easily escape as well if you want to. Just return the bandanna to Copeland to complete the mission.
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