The white opera gloves found under Stephen's bed which were clearly used by the killer, belonged to David.

Three weeks before the killings David bought some opera gloves for a ball. These gloves were kept in a drawer in David’s room. The killer used these gloves when he shot Margaret and Laniet, but when he tried to shoot Stephen, the young lad awoke and the first shot went through his hand and grazed his head, causing him to bleed profusely. At this point it appears that the killer had a misfire and had to remove the gloves to fix the gun and they ended up on the floor.  During this lapse Stephen retaliated and began to fight for his life with the killer, but his attacker overpowered and throttled him with his own T-shirt.  We know this because when Stephen was found the shirt was bunched up around his neck and there were also abrasions found on his neck. When Stephen became incapacitated and/or the gun became operational again, the killer finished Stephen off with a fatal shot to the head. David’s very bloody gloves were later found under Stephen’s bed and must have been kicked or thrown there during or after the struggle.

If Robin Bain had been the murderer and was intent on suicide then the crucial question has to be why on earth would he be wearing gloves to avoid leaving fingerprints?

Evidence shows that the killer removed the gloves after the gun misfired during his struggle with Stephen.  If it wasn't for this struggle taking place, the killer would have been able to do his deed leaving no fingerprints on the rifle and leaving the gloves clean and unsullied.  This would have suited David, if he was attempting to commit the murders and then frame his father for them, and the gloves would not have become incriminating evidence which they did, all covered in blood and clearly worn by the killer. 

If you believe David is the killer then it is clear that if things had gone to plan and Stephen had not put up a fight, neither the gloves, nor the spectacle lense nor the jersey fibres under Stephen's fingernails nor the newly washed murder clothes would have been left behind as incriminating evidence and he might have got away with it and never been convicted in the first trial.

Those who believe that Robin was the killer have to ask the question, why would he wear gloves? If he felt it necessary to wear gloves, then why use David's? He had his own pair of gloves in his caravan. Was he trying to frame David?  If so, why leave the computer message saying that David is the only one who deserved to stay?  There is a direct contradiction here, which doesn't make sense.

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