After oh kai kai is completed Sharon will tell you she has bad news for you. There have been a couple murders in Briar Valley and that the investigator is tying you into them and making you a suspect. She will send you to Brair Valley to speak with Finnegra.
Once in Briar Valley Finnegra will be located next to the sheriff station. After you have spoken to him your quest will begin
Sneak into Finnegras house which is located in Briar Valley and still his evidence book. There will be a sign saying “Finnegra’s House” on the front of the house. Read the evidence book and speak to the 4 suspects: Steve, Mitch, Brandon, and Damien who are all located throughout Briar Valley
Once you talk to all of them head back to Finnegra to accuse one of them. After you have accused one of them they will speak to you and will have you meet whichever one you accused behind the Sheriff station
Follow the Sand path behind the sheriff station and at the end you will see the one you accused and you will have to kill them.
Finnegra Coordinates: X:-733 Y:65 Z:-464
Steve Coordinates: X:-741 Y:65 Z:-394
Mitch Coordinates: X:-753 Y:65 Z:-393
Brandon Coordinates: X:-718 Y:65 Z:-460
Damien Coordinates: X:-739 Y:66 Z:-465