Why then did he sign the search warrant for Cohen’s office and home raid? Everything they scooped from his home and office by the SDNY which is the massively corrupt district in New York will find something to incriminate Trump! This fight is not even close to being over! Rosenstein and Mueller are the biggest evilest liars on the face of this earth! Their hatred towards Trump knows no limits...they will continue to search under every rock for incriminating dirt to force Trump to his knees! DON’T FALL FOR THE LIE!!
Mueller didn't. He said that he found evidence against Cohen that didn't relate to his investigation, so he referred it to the U.S. Attorney for the Southern District of New York. They got the warrant.
There is speculation that Mueller's referral to the SDNY involved Cohen's payoffs to Stormy Daniels, but I suspect it is nothing of the kind-- probably some fraud relating to Cohen's taxi business.