If I visit or contact him, what will happen?

the only people who will know you have been to see him is the authority's were he is being held,and obviously anyone you tell,and him,its not against the law to visit,unless you were a prosecution witness and your not,so your ok,if you put ion any statement and there is any charges brought then you may well have to give evidence,i think if there is any chance of him being charged in relation to yourself or others you know you may be better off distancing yourself,but that's up to you,good luck.