The Serious Fraud Office began a two-week “trial of the facts” on the case of former Morgan Grenfell fund manager Peter Young this week.
The case, which is taking place at the Old Bailey in London, will look to ascertain whether Young is culpable for a £220m fraud at the firm in 1996.
No verdict will be passed on the charge of conspiracy to defraud and five charges of breaching the Financial Services Act, after Young was found unfit to stand trial at a Southwark court hearing last December.
Young, who managed Morgan Grenfell's European and European growth funds in the early 1990s, now dresses as a woman and prefers to be known as Beth.
The trial of the facts, which is usually reserved for use in murder cases where the defendant pleads insanity, will simply look to determine whether Young carried out the alleged actions.
The judge, the Honourable Mr Justice Jackson, has enforced a reporting ban on the case ahead of the criminal case against Young's former colleague Stuart Armer and former stockbroker Erik Langaker, which is due to start on September 17.
A spokesman for the SFO said the trial against Armer and Langaker is estimated to last six months.