The trial court erred when it failed to hold a second competency hearing, following a substantial change of circumstances since the original hearing. Prior to appellant’s trial for attempted murder and other offenses, the trial court found him competent to stand trial pursuant to Penal Code section 1368. Nine months later, at the beginning of the trial, appellant jumped from the second tier of the jail. His attorney then questioned whether he was competent to stand trial. The trial court concluded that there was not enough of a change of circumstance to warrant a change in the initial competency determination. Following conviction, appellant argued on appeal that the trial court erred by failing to conduct a second competency hearing. The appellate court agreed and reversed. Upon presentation of substantial evidence showing a new evidence giving rise to a serious doubt about the validity of the original competency finding, the trial court must hold a subsequent competency hearing. The same standard of proof applies in the first and subsequent decisions whether to hold a hearing. Here, substantial evidence showed a substantial change of circumstance, which triggered the requirement that a subsequent competency hearing be held. The psychiatric report submitted to the court concluded that appellant’s mental state had decompensated and that he would likely be unable to assist in his defense. Therefore, a second hearing should have been held. Remand was required with directions to determine whether a retrospective competency hearing should be held.