Yusuf Zuck stayed for three days at Four Flat Mountains, because he wanted to give Raul Graves and Crystal Locke time to reunite, so three days later he left Four Flat Mountains with Crystal Locke, and Raul Graves also left, his whereabouts unknown.
Of course, from now on, Crystal Locke would be the secret contact person. All intelligence from Raul Graves would be passed on to Crystal Locke, and then relayed to Yusuf Zuck, because besides his own wife, Raul Graves didn't trust anyone.
After all, when it comes to matters of life and death, one can't be too careful.
Moreover, regarding Raul Graves becoming a Heavenly Demon undercover agent, Yusuf Zuck didn't want to tell others. Besides informing Porter Ray, no third person was allowed to know, because the fewer people who know, the more responsible it is for Raul Graves.
