| Burn marks on tracksuit bottoms worn by an Arbroath youth accused of setting fire to his girlfriend could be attributed to “flame wash”, an expert witness told the High Court in Livingston today. Stewart Blackburn (18) denies that on April 25, at Fraser Place and Newton Avenue, Arbroath, he assaulted Jessica McCagh by throwing petrol over her, a bed, and setting fire to her whereby she was so injured she died in hospital, and he murdered her.
In cross examination, forensic fire investigator Rebecca Peplar (34), who began her career with Tayside Police and now works as manager of a forensic science company in Reading, said there was some damage at a low level to tracksuit bottoms worn by Blackburn.
There were two holes at the front of one leg and another small hole at the back.
She said this could be attributed to flame wash, which she explained was the foremost point of a flame travelling rapidly over a surface as paper ignited.
However, the evidence was inconclusive and could neither confirm nor refute the presence of flame wash.
Defence Counsel Neil Murray referred her to her report and a section dealing with accounts by witnesses.
He read, “It has been reported that witnesses who have had direct involvement in a fire quite often find it difficult to accurately recall disturbing aspects of the incident and may exaggerate sights they have never previously experienced.”
Ms Peplar agreed this was often the case.
She confirmed another fire investigator had been present when she conducted her examination of Blackburn’s flat in Bloomfield Road, Arbroath.
Asked if she discussed the examination, she said the two experts had talked about some technical aspects and had played “devil’s advocate” to test possible interpretations of the scene.
Mr Murray later asked her about witness accounts in which they said they heard two “booms”.
He asked if there could have been an explosion and she said there was no physical evidence to support what people commonly understood as an explosion.
She said that there would be an increase in pressure as a consequence of vapour igniting, which could be sufficient to slam a door shut and agreed with Counsel that this could explain one of the booms said to have been heard.
Referring to a DVD shown to jurors yesterday in which attempts were made to replicate the start of the fire in which Jessica sustained fatal injuries, Mr Murray asked about the methods the witness employed.
Ms Peplar conceded that she had been unable to find an identical canister, or jerry can, to the one found in the Bloomfield Road flat.
She also accepted she had not seen the visual recording of the interview given by Stewart Blackburn to police officers in which he described “slapping” a petrol can.
Nor had she seen the bodily movements as he described slapping the can.
The trial continues. |
