If he was arrested on Monday he should either have been released or charged within 24 hours. If he was charged he has to appear in the Magistrates’ Court at the next opportunity. This would have been Wednesday at the latest. The police have no powers to detain him longer than that without bringing him before a court (apart from the exceptions that Buenchico mentions which do not seem to apply here).
The likelihood is that he has been charged, brought before a court, the court has refused him bail and remanded him in custody.