Peter Hentschel from the ESR was the only forensic expert to see or measure the bloody sock prints, his opinion was that they were a match for David’s foot size not Robins. Results from Experiments done many years later conflicted with his original opinion, but then those experiments relied on guesswork as to how much actual blood was applied to the socks used in the experiments.
As photographs of the original prints “that would have backed up Hentschel’s testimony” did not develop Counterspin has elected to label this evidence as inconclusive.
Forensic experts found bloody sock prints in the hallway and in Laniet's room. These undoubtedly were made by the killer and were created when he stepped in blood on the floor in Stephen's room.This was another item that helped lead to the retrial.
Detective Weir, in his evidence relating to the footprints that showed up under the luminol test, said that one measured 24 cm and another 28 cm. At the first trial they were assumed to be David's, but the appeal case argued that they were too short to be his because David's feet were measured at 300mm. This is not logical simply because if that was the case then the print of 24 cm could not have been made by either Robin or David because it was smaller than either suspect, as it says below Mr. Hentschel the ESR scientist could not measure the complete toe to heal print because it was not there.
The 280 mm sock prints were not visible to the naked eye but only through a luminal test, which indicates that the prints were faint and increases the likelihood, as attested by the expert witness for the prosecution that the prints would be shorter than the foot by 20mm or more. This would happen because the main pressure point on the ball of the foot is some 20mm from the end of the foot and on the big toe about 10mm, meaning that a small amount of blood on a sock worn by a person with a 300mm foot is likely to leave a 280mm impression.
Robin's feet were measured at 270mm. If these prints were to be left by Robin then they are 10mm longer than the size of his feet, so while the Defense argument might provide an excuse for the prints not being left by David, they certainly don't fit well with support the alternative option.
This argument became highly technical and the Defense sufficiently succeeded in casting sufficient doubt over the original assumption to make this irrelevant.
Mr. Hentschel from the ESR was the first man to measure the luminal footprints in the Bain house. His testimony was that he measured the prints, with the biggest print 280mm long. Mr. Hentschel measured the prints only from the toe "area" to the heel "area", and therefore the full print could have been larger. He said that it was a complete print in that it comprised of the toes and the heel however he said that it was not the"complete toe and heal" he also said he measured the area of strongest luminance, not all the luminance. David Bains prints are said to be 300mm so going by Mr. Hentschel’s testimony David could easily have made these prints because as Hentschel said the prints were not complete from the tip of the toe to the back of the heal.
Robins feet measured 270mm there were tests done by both defense and prosecution at the trial ESR forensic scientist Kevan Walsh, for the prosecution, told the court how he performed tests with socks soaked in animal blood, placed on to card to take off the excess, and then on to carpet. He used his own feet, at 298mm long to mimic David and a volunteer with feet the size of Robin for his testing. He measured the resulting prints after spraying them with luminal.
Mr. Walsh said the testing of his own foot, to mimic David, got an average size sock print walking on carpet of 297mm, and nothing smaller than 286mm. With testing of a foot the size of Robin's, Mr. Walsh said the average size bloody sock print was 282mm.
My Walsh's conclusions were contradictory. Robin was found with socks and shoes on, neither of which had blood on them. David was found with bloody socks on, but the blood may have been just from moving innocently through the house after the paper round
Questions from the Bain trial judge shed new light on footprint evidence in the High Court retrial in Christchurch in 2009.
ESR scientist Mr. Hentschel, who saw the original footprints which were measured at 280mm, said they had to have been made by a foot bigger than 280mm.
David Bain's foot is 300mm while his father Robin's foot was 270mm.
Both defense and Crown experiments were done by dipping a foot in a tray containing several milliliters of pig or cow blood, walking off the excess and then walking on carpet.
The prints were then sprayed with luminal, a chemical which reacts with blood and glows in the dark, and then measured.
But at trial in 2009 questions from Justice Graham Panckhurst, to Crown witness Environment Research and Science (ESR) scientist Kevan Walsh highlighted that no tests were done by first standing on bloodied carpet which would have mimicked the actual footprints to some degree although the amount of blood to apply would still be total guesswork.
Another question reminded the jury the footprints tested at the scene were not visible to the naked eye whereas the footprints in the experiments were clearly visible even before the luminal testing. Justice Panckhurst noted “no tests were done by first standing on bloodied carpet which would have mimicked the actual footprints”.
Conclusion: The footprint evidence can possibly be considered inconclusive because its impossible to replicate bloody sock-prints especially when there are no photographs of them, one can only really rely on the opinion of ESR scientist Peter Hentschel "the only expert to see the prints" and he said the 280 mm print "was not the"complete toe and heal" which of course means the foot that made the bloody sock prints was larger than 280 mm, Davids were larger by 20mm.