The trial by jury of Brian Vella, who is charged with the murder of an elderly couple, was yesterday dissolved after the judge ruled there was the risk that reference to the evidence of a key witness, who was deemed incompetent to testify at this stage, could lead to a miscarriage of justice.

The trial was dissolved after Mr Justice Joseph Galea Debono upheld a request by Vella's defence counsel who objected to Dominic Bonnici's testimony on the grounds that once Bonnici was an accomplice in the alleged double murder and was still awaiting judgment he was not a competent witness.

Once Bonnici's testimony was deemed inadmissible, reference to it by Police Commissioner John Rizzo, who testified on Tuesday, was now merely hearsay, the defence lawyers argued.

However, there now existed the risk that jurors would be negatively prejudiced by the Police Commissioner's evidence and, therefore, the risk that Vella's right to a fair trial would be prejudiced, they added.

Vella, 34, of Hamrun is pleading not guilty to the murder of 79-year-old Gerald Grima and his 63-year-old wife Josephine in their Sta Lucija apartment on February 10, 2000.

The prosecution is claiming that on February 10, 2000, Vella met with Dominic Bonnici and Robert Borg at the Nationalist Party Club in Sta Lucija. There, Vella suggested they burgle the house of the Grimas and that evening the three made their way into the couple's home, bound them, gagged them and stole their valuables.

The couple were found lying dead in their apartment, bound and gagged, on February 17, 2000.

When Senior Counsel to the Republic Mark Said, prosecuting, called Bonnici to the witness stand on Tuesday Dr Anglu Farrugia and Dr Kris Busietta, for Vella, objected.

They argued that Bonnici was not a competent witness according to law because he was an accomplice to charges brought against Vella and his (Bonnici's) case had not yet been decided.

Dr Said, however, noted that the defence should have made its request in the preliminary stage of the trial, adding that Bonnici had testified in the compilation of evidence against Vella.

Mr Justice Galea Debono ruled that the prosecution was right in saying that the defence should have made the request at an earlier stage. However, in view of the fact that the defence could not have known with certainty whether Bonnici's case would have been decided, the judge allowed the defence to put forward its request.

"However, even if the court upheld the defence's objection regarding Dominic Bonnici's testimony... the court could foresee another serious problem in the administration of justice that could seriously impinge on the accused's right to a fair trial," the judge said.

The court had only been informed that Bonnici's case was still pending after several witnesses had testified. Among them was the Police Commissioner who gave an overview of his investigations and an account of how Bonnici had admitted his involvement and also spoke about Vella's involvement.

Mr Justice Galea Debono went on to explain that now that Bonnici would no longer testify, the Police Commissioner's reference to Bonnici's admission was merely hearsay. In the light of this unpredicted development there was the risk that the jurors would be negatively influenced by the Police Commissioner's testimony.

This created the manifest danger of a miscarriage of justice since Vella's right to a fair trial could be prejudiced.

Due to these unpredictable developments the court did not think it would be just or prudent to allow the trial to continue being heard by the same jurors.

For these reasons he dissolved the jury and put off the case sine die to be heard by different jurors.

Vella remains detained under arrest, as he was before his trial started on Monday.