A UN relief worker claimed he was targeted by an Israeli army sniper just after his colleague had fallen wounded.
Iain Hook was working for the UN when he was killed
An inquest into the death of UN worker Iain Hook has reopened at Ipswich.
Paul Wolstenholme's written evidence said he was in the compound at the time of the shooting and a sniper's red laser beam fell on him.
Det Supt Roy Lambert showed pictures to the inquest which he said indicated the sniper knew he was shooting into the UN compound at Jenin and had a clear view.
Iain Hook, 54, of Felixstowe, Suffolk, died as he tried to negotiate the rescue of his colleagues inside the West Bank refugee camp in Jenin, where he had been working for six weeks.
Mr Hook and fellow workers were trapped in the compound for several hours in November 2002 after Israeli defence forces entered Jenin.
Palestinian gunmen fired at the troops and the UN office was hit by a hail of bullets in the resulting gun battle.
Home Office pathologist Dr Michael Heath told the inquest that Mr Hook had been hit with a bullet fired from a medium to high velocity weapon. It had shattered his pelvis.
He said the wound was so serious that "death was inevitable".
Several witnesses are expected to bring evidence to the inquest including Clare Short, the former cabinet minister responsible for overseas development.
Mr Wolstenholme could not attend the inquest but submitted documentary evidence which stated that the Israeli army had delayed an ambulance which was sent to take the wounded Mr Hook to hospital.
His statement said that he had sent a letter to Ms Short expressing his concern about the delayed ambulance and that the Israeli special forces had not given a full account of themselves.
Mr Wolstenholme said if the incident was not fully investigated then it would have become "open season" on shooting United Nations staff.
Former soldier Iain Hook had been involved in several relief projects in East Timor, Afghanistan and Serbia.
His former employer John Adlam paid tribute to his work in rebuilding a hospital in Pristina, capital of the Serbian province of Kosovo, in 1999.