It’s number of jails, not prisons. The people there are detainees (those who have not yet been convicted), those sentenced to a year or less ( you don’t go to state prison unless your sentence is a year or more) those who are convicted, sentenced and awaiting transfer to a state prison and a very few who might be sent from state prison back to Riker’s if they are going to testify in another matter in NYC.
He’s not a public defender; he’s a private defence attorney.