A pathologist said he was unsure if a stab to the chest or a shot to the face caused Mohammed Raja's death.
The Brighton landlord was assassinated by two hitmen dressed as gardeners at his home.
Yesterday, Dr Richard Shephard told the Old Bailey he carried out a post-mortem examination on the body of 62-year-old Mr Raja on July 3, 1999, the day after his death.
He said Mr Raja suffered five stab wounds to the chest area, one of which ruptured his aorta.
Dr Shephard said either this or the gunshot wound to the face could have provided the killer blow.
On examination, Mr Raja was found to have:
A 4.5cm wound passing through his sixth left rib
A 6cm stab to the chest
A 4.5cm wound to the right side of the chest
A 3cm wound piercing the right abdominal cavity
A 3cm wound puncturing the aorta and causing internal bleeding.
He said there was also a hole measuring 10cm by 7cm on the left side of Mr Raja's face.
Dr Shephard told the jury: "It would suggest the gun was in very close proximity to the left side of Mr Raja's face."
The court heard the cartridge fired was made by a Hull firm and bought in 1995 or 1996. A cartridge made by the same firm was found in the back of a burnt-out van on the day of the murder.
Forensic expert Martin Whittaker told the court a knife recovered from the same van contained DNA matching that of Mr Raja.
Earlier Mr Whittaker said a sample of a blood smear on Mr Raja's front door was compared with a cheek swab taken from David Croke. He said the DNA samples matched.
The prosecution alleges Croke, 59, of Bolney Road, Moulsecoomb, Brighton, Robert Knapp, 53, of Convent Street, Abbeyfeale, Co Limerick, were paid by Nicholas Hoogstraten to carry out the killing.
All three deny murder and Hoogstraten, of High Cross estate, Framfield, near Heathfield, also denies conspiracy to murder. The trial continues.
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