Did you get the perfume from Crock?Spoiler!!!
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You have to apply the Perfume on a particular dummy. The dummy that can be brought down through some controls and is located on the upper Marten's Bluff. If you do it correctly, there should be a message telling you something like that a piercing scream is heard. By looking on your radar you can see a yellow dot moving towards the main gates.
P.S. Remember to leave the gates open or the Rapax won't be able to get in.
You can kill him direct or use the control levers to crush him.
Good Luck!