DI Lang's notes for police report

Author's note: Detective Inspector Lang is the chief investigating officer in The Ghost of Helen Addison. Towards the end of the novel he considers a rational rather than a supernatural explanation for what has unfolded. This was derived from notes Lang had written in preparation for his police report, but which don't appear in the novel.
SPOILER ALERT

Rattray was extremely narcissistic. He [as outlined in sect.1] had become fascinated by his grandfather, the thirteenth Baron of Caradyne. Rattray, like his hero, sought to self-justify his deviancy by expressing it through quite complex occult melodrama. Rattray was indeed delusional, yet although he had convinced himself of the authenticity of his pseudo-religious rituals I contend his confidence in their power was not absolute, and he used an entirely practical means by which to draw his victims from their beds during the night. He was a highly manipulative individual, skilled at synthesising rapport, and volumes discovered in his attic show he had a keen interest in covert hypnosis techniques.
Therefore:
Helen Addison: Rattray – the ‘Tark’ from victim’s diary [see sect.1] – had some psychological hold over her [Speculation: could this have gone back to her childhood? He would have known her all her life, and Mr Stuart Addison informed me yesterday that Rattray babysat for his daughter when she was a child]. She was drawn by some subconscious seed planted by Rattray via said hypnosis. This, combined with the effects of antihistamines (proven to make some people susceptible to somnambulism – and she had been known to sleepwalk, albeit only during childhood [Rattray may have witnessed this]) taken by the victim for an allergy, was sufficient to coax her from her bed.
Robert McKee: Easiest to explain. He was doped on ketamine hydrochloride (spiked by Rattray, who often cooked meals for him), benzodiazepine (which he had been prescribed by his GP Dr JA Fitzpatrick for anxiety), and, countering these, the stimulating effects of the anxiety itself and possibly a natural psychoactive (some traces of fungi found in Rattray’s bin have been sent for analysis) as well as the psychoactive side-effects of the ketamine. Combined, these induced a profoundly altered state; there would have been no need to use any psychological programming upon McKee. [Speculation: Rattray performed some terrifying piece of theatre on the night of the attack upon Ms Whitton to drive McKee into the woods]. Unfortunately, have been unable to interview McKee due to ongoing mental distress.
Eva Whitton: On the night she was attacked, Ms Whitton admitted to registrar at Oban A&E to having taken an illegally procured substance, probably some form of ersatz barbiturate, before going to bed. This was probably purchased from one Alexander Dreghorn, a suspected drug dealer from whom Whitton also bought scrap metals. Tranquilisers are a known cause of somnambulism and upon questioning Ms Whitton stated she was known to sleepwalk from time to time – Rattray was therefore doubly fortuitous. [Speculation: could Rattray, having babysat for Ms Addison during childhood, and through some historical conversation with Ms Whitton, have known that both women had a predilection to somnambulism which could be exploited through subtle psychological manipulation?] Also, Rattray had a friendly business relationship with Ms Whitton and had opportunity to perform the same auto-suggestive technique he had used on Ms Addison. Ms Whitton has confirmed that she was indeed engaged in conversation by the perpetrator during the day prior to the attack upon her person. Furthermore, she recalls that Rattray steered that conversation to the subject of Ms Addison’s murder, which was the cause of great disturbance in Ms Whitton’s mind, as she knew and admired the victim. Upon my probing Ms Whitton said Rattray may have dwelled upon the subject of Ms Addison’s unexplained night walk, which preceded her murder. I propose that at this point in the conversation Rattray, using carefully pre-constructed linguistic data, obliquely planted in Ms Whitton’s unconscious the desire that she too should sleepwalk that very night. [Speculation: He may have subtly suggested that in doing so Ms Whitton could somehow retrospectively save Ms Addison. It is impossible to incite someone into acting self-destructively, therefore the post-hypnotic suggestions seeded in both women’s minds would have been associated with something benign and/or mundane].
Leo Griffin: Griffin did not speak with Rattray the day before his night walk and therefore could not have been manipulated by him. Anyway, he was entirely conscious before and during his encounter with Rattray on the island of Innisdubh. However: heavy drinker, suffers from night terrors; may have gone for early walk and been drawn to island out of sheer curiosity [Speculation: saw candle lights? Saw boat over there? (check if such objects would be visible from mainland). Just nosey? A nosey bastard who got lucky? But he rang me and told me it was Rattray over there before he had gone over himself!!!??? Perhaps he just had a sharp instinct for falsehood e.g. Rattray’s body language or choice of words gave him away. But what about other, accurate info he had passed to me earlier in investigation?!]
Addendum: As for the cooperation of Mr Leomaris Griffin, I can only commend his perceptiveness. I cannot reasonably account for all of the information he brought to bear on the case and I would recommend his utilisation in future operations.