Video experiments showing how blood travels after being exhaled from the nose and mouth were shown at the Sion Jenkins appeal.

The tests claimed to throw doubt on prosecution assertions exhaled blood falls only within a few centimetres from the victim.

The prosecution claimed blood from 13-year-old Billie-Jo Jenkins could only have got on to Jenkins' clothes because he was close to her as he battered his teenage foster daughter to death with an 18-inch metal tent spike.

But at Jenkins' second appeal to overturn his murder conviction, Professor Robert Schroter yesterday dismissed the idea exhaled blood falls only within a small distance.

Professor Schroter, professor of bioengineering at Imperial College, London, said gentle currents of air could have carried the blood droplets considerable distances and not necessarily in line with the ejection trajectory.

The defence claimed this was significant because Billie-Jo's nose would not have needed to be pointed at any particular angle to produce blood spray patterns.

They say the blood particles could have got on to Jenkins' clothes when a blood bubble burst in her nose as he crouched and put her in the recovery position after finding her bleeding to death.

She was lying on the patio of the family home in Lower Park Road, Hastings, in February 1997.

Jenkins' defence counsel, Clare Montgomery, QC, said the Crown's experts did not consider the science properly before giving their opinions.

Three new videos showing blood exhalation experiments were screened yesterday in an effort to cast uncertainty on the prosecution's blood spots theory.

One showed lungs physiologist Professor David Denison having his own blood inserted into his nostrils while he laid on his side and exhaled through his nose.

Father-of-four Jenkins, sitting behind steel bars in Court Four of London's Appeal Court, looked away as the experiment showed blood spatter beyond just a few centimetres on to walls and the side of a bath.

In another experiment, Professor Denison inhaled blood into his mouth before spitting it out at a target.

Later, the three appeal judges - Lord Justice Rose, Mr Justice Curtis and Mr Justice Wakerley - heard only 25 per cent of the incriminating blood spots now remained.

The spots had helped convict Jenkins at his trial at Lewes Crown Court in July 1998.

Out of 158 microscopic spots found on his clothes, only about 40 still exist.

Most had fallen off the clothes, which were yesterday mounted on boards, while others had been removed for DNA testing.

Jenkins points to the fact that part of a plastic binliner was found stuffed deep into one of Billie-Jo's nostrils. A mentally-ill man, Mr X, who had an obsession with pushing bits of plastic bag into his mouth and nose, was in the vicinity at the time of the murder.

Forensic scientist Adrian Wain yesterday said he had never before come across a case in which part of a binliner had been stuffed up the nose of a murder victim.

He agreed it was "a highly unusual and strange feature of this case".

Jenkins, who was headteacher-designate at the all-boys William Parker School in Hastings when charged with murder, has always maintained his innocence.

The hearing was adjourned until Monday.