Reversed and remanded for a new trial. We agree with appellant that the trial court failed to conduct a proper inquiry when the state called an important, but previously undisclosed witness at trial. See Brey v. State, 382 So.2d 395 (Fla. 4th DCA 1980). Instead of determining the circumstances of the discovery violation and requiring the state to demonstrate the lack of prejudice to the juvenile accused, the court imposed the burden on the accused to demonstrate prejudice. This does not satisfy the procedure contemplated by Richardson v. State, 246 So.2d 771 (Fla. 1971).