Personal Q (good advice pls)!!!!!!!?

ok so last sataday night me and my mates went town sepratley from the boys. just as me and my friends were next in que to go into a club i got a phone call from one of my boyfriends mate saying my boyfriend had just been rushed to hospital after he got smashed in the face. hes ok now but the police are involved as the criminal is aparently an illegal immargrant! we have heard many stories about the guy that hit my BF detials like his name and where he comes from ETC, aparently hes well known and not for good reasons either..well anyway the club in which the lads where in when my boyfriend got struck theres a bouncer. the bouncer knows who the guy is and where he lives but he doesnt want to give up any information to the police cos he dont want the guy to come for him! no matter what the police have said to the bounce hes not telling them anything. now me and my boyfriend need him to give this information so we can take this guy to court to get him deported and charged what can i do?