cnn newsroom. we re grateful to you have this afternoon. i m boris sanchez. hi, everyone. it i m jessica dean. political lines deepening, law enforcement preparing for what would be a first in american history. the criminal indictment of a former president. the key witness in a case against donald trump is expected to be challenged today before a grand jury in new york. a former legal advisor to michael cohen telling cnn testifying at the request of donald trump s attorneys. look at video of costello arriving at the courthouse moments ago. robert costello saying he ll offer evidence that contradicts cohen. cohen, who once labeled himself trump s fixer said he paid adult film actress stormy daniels $130,000 in the weeks before the 2016 election for her silence on an alleged affair with donald trump. now, that was a campaign finance violation, as cohen lied on forms to cover up that payment. in 2018. you may recall. cohen cut a deal with federal prosecutors and adds mitte
prosecutors and adds mitted he acteds in coordination with and at the direction of individual one. individual one was later identified as trump. the former president has denied the affair took place, but over the weekend he revealed he thinks he s going to be arrested tomorrow, ending his online post with a call to protest and take our nation back. the manhattan d.a. is not commenting on any arrest, but the nypd has set up cameras and barricades in recent days around the courthouse. sources say that new york authorities are extremely concerned about security and crowds there. let s get you the very latest from the manhattan courtroom with cnn senior legal affairs correspondent paula reed following all developments. do we know how robert costello will try to contradict michael cohen before the grand jury? reporter: we have some idea. a witness requested by the