AFTER waiting four-and-a-half years, a former Government scientist has been cleared of killing a colleague when a secret test explosion went wrong.

The prosecution offered no evidence against Maurice Marshall, who used to head the MoD Science Technology Laboratory at Fort Halstead, near Orpington.

Mr Marshall, aged 58, from Tunbridge Wells, resigned after being charged with manslaughter through gross negligence, the Old Bailey heard.

The case involved the death of Terry Jupp, who suffered up to 90 per cent burns when a 10kg blast at an MoD site in Shoeburyness, Essex, went wrong in August 2002.

Despite being treated at a hospital's specialist burns unit, the 46-year-old died six days later.

Mr Marshall, one of the world's leading explosives experts, had been responsible for mixing the charge.

He was accused of not warning Mr Jupp how dangerous it was.

Fellow scientist Robert Weighill, aged 57, from Sevenoaks, and Mr Marshall were charged following an investigation.

But Mr Weighill was cleared in August 2005 when an Old Bailey judge ruled there was not enough evidence for a trial.

Last week, prosecutor Gareth Patterson told the court the evidence against Mr Marshall had recently been reviewed.

Mr Patterson said: "The decision has been taken there is no longer a reasonable prospect of conviction."

Mr Marshall, who has always maintained his innocence, was not in court for the hearing.