This is always difficult for the advocate. On the one hand, the prosecution have to prove the case . The defendant does not have to prove anything. Indeed, sometimes counsel knows that the judge won't stop the case at the close of the prosecution's case because they have not established the case enough for any jury to convict ("no case to answer"), and counsel decides not to call any evidence, even that of the defendant. (If you are wondering, that is often because counsel thinks that the defendant will come across so badly in the witness box that any doubt of guilt the jury has will be removed by the defendant !)
Now, the other side of that is that the defendant giving evidence will be asked whether or will volunteer, that someone witnessed the events. Prosecuting counsel will immediately ask "Do you know this person? Have you seen them lately? Have you told them of the case? Are they here today? " That is all to suggest that the witness is nit being called because the account they would give would be damaging to the defendant, on proper examination.
The reason why I asked whether the witness had signed a statement is that, if called and hostile to the defendant, at least his statement can be put in front of him and he can be shown to be giving two different versions and thus discredited, as someone who says whatever suits his mood at the time.
In the end, you decide whether to call him by establishing, reminding him of his statement, what he will say on the day, what version he will give. If in doubt, you don't and you dismiss the prosecution suggestions about his absence by reminding the court that it is their, the prosecution's, job to call poroive guilt, not yours to prove innocence.