Sir,what testimony he has given to the police before? If he is a material witness and a eye - witness of the incident , so if he denies before court and gives evidence in your favour , it no doubt puts case in your favour.. But not 100 percent as thier are other witnesses also.. As far the security of money and trust factor is concerned , it depends how much faith you have in your lawyer.. In such cases money is not given in advance , and is kept with someone who is trusted by both the parties.. Once he gives evidence in your favour, the money will be given to the witness..I suggest not to give in advance.. If you want to discuss in detail , u kindly urge you to contact me throug phone consultation