Evidence given in the 2009 retrial lays a firm foundation to the idea that David was attempting, with his mother's encouragement, to supplant Robin's position as head of the household. At age 22, when most young men have left home, David was firmly refusing to go out into the world and make his own way. Instead he was attempting to wrest control of the house and future plans for it, from his father. He had spent much of the time he was on the dole working on the section at 65 Every Street trying to realise his mother's plans for a new house come retreat by preparing a garden. Not only do witnesses describe this but also one witnesses reveals that David already had plans with what he was going to do with the house within a few days of the murders, which suggests that he had longed planned it.
1. Karam has repeatedly claimed that David had no motive to commit the murders:
1.1. In the Innocent booklet (p26) Karam stated “In summary it can be said without contradiction, that no motive, no mental predisposition, or precipitating circumstance has ever been put forward in relation to David Bain, yet each of those elements presents themselves with Robin.”
1.2. In Bain and Beyond page 19: “No evidence of motive or mental disorder has ever been attributed to David Bain.”
1.3. In Bain and Beyond on p201: “There was no motive or mental predisposition.”
1.4. In David & Goliath p101 “It is well established in this case that no reasonable motive has ever been proposed for David Bain to have planned and executed this crime”.
1.5. In David & Goliath p221 “David had no known motive. Nothing that hs come to light has thrown any light on anything that may have set him off on this path of destruction.”
2. The original prosecutor, Bill Wright suggested that David saw that the plans for the house were bogged down and decided to kill the family for the inheritance so he would have full control and build the house himself. The inheritance at the time was worth in the region of $300,000. Karam admits this himself on page 63 of David and Goliath when he mentions this:
“The Crown attempted to allude to financial gain as being his motive, but all accounts I have heard, and certainly my readings of the file, indicate that this proposition had little to sustain it, and had little impact on the proceedings.”
3. There is evidence of considerable conflict between David and his father and David had fantasies about usurping the fatherly role. This is evident in the testimony that David had taken over the head role of the household, a position normally held by the father. Such a conflict can have serious repercussions:
3.1 This motive is supported in testimony from a witness in the retrial, a friend of David's who testified that David already had a plan to sell the house, even before he was arrested on Friday 24 June: (Q = counsel; A = Rebecca Hemming)
Q. Did you talk about the funerals in any other way as well?
A. Yep, he knew that he wanted Arawa to wear the ball gown that she was either going to wear or had worn at a ball. That he hadn't decided about the clothes for the rest of the family yet and that he was hoping to be able to get in the house the next day to be able to go and choose, but he hadn't particularly got any ideas about that. I’d asked about, you know, what his plans, you know, had he started thinking about what life might be like after funeral and he said that he was thinking he was going to sell the house and buy somewhere for himself so that he would have a home.
Q. Did he mention where the money was going to come from?
A. Yeah he was quite concerned that he managed to get the money back from the Meders, because he was a bit anxious that with the amount of money, if it, you know, kept growing with interest and what have you, they would not be in a position to be able to repay it.
3.1. Another friend testified that David's mother had stated that David had taken over the head of house:
Q. Did Margaret say anything at all about David’s role in the family?
A. Yes she said that basically David had taken over being head of the house while Robin was working down at Taieri Mouth at the school. She said that he stayed down there for the whole week because it wasn’t worth his while coming home, it was too far, and that David had taken over the day-to-day, um, father things that the male of the household does.
3.2. David himself corroborates this situation, from the Binnie / Bain interview, page 4:
Q. Well, yes you do at - but there , there's also the, a discussion in the evidence that you felt that your father was attempting to exert control, that he did this by laying guilt trips on you in particular and that in that sense he was seen by you as somewhat manipulative?
A . Yes . Well it seemed that, I mean my father was quite a strong character, you know, very - he was a good teacher, articulate, creative et cetera et cetera but with - in that family dynamic and nearer the end of that time, well , for the, for the two years at least in the lead up to '94 he became very withdrawn and shrunken and when he was - in the household. When he was outside of the house he sort of became his old self which I guess is why I have - I still have you know, good feelings towards my father at the time we shared a lot of time together and especially in choral situations or doing shows. I mean I, I had to do a show for the youth group I was involved with, um, called "Trial by Jury" and he came, helped me do all the set design and construction 'cos I knew you know, he and I worked well together so there was that, that was that aspect of our relationship . The manipulative aspect of things within the household though, that was what caused me difficulty because I couldn't - I had the direct command , so to speak, from my mother that this was how the situation should be but then my father, who had every right to want to be, you know, equally contributing to the household in decisions with in the household, his only way of having any impact so, whatsoever, was to be manipulative or to try and come in from the side whereas Mum . . .
3.3. In the retrial, another friend of David’s testified that David said he would be sleeping in one of two planned master bedrooms:
A. Yes I asked him where he lived and he said that he lived in Anderson’s Bay in an old house was starting to fall down so they were, they had plans to build a new one. And he was sort of quite involved with that and he was going to be helping to build the new house.
Q. Did he go into a bit of detail about that and what the plans were?
A. Yes he talked about there would be a workshop and there would be two large bedrooms joined by a bathroom and he said one of the bedrooms would be for me and I sort of joked and said, “Oh is the other bedroom for your mum and dad?”, and he said, “Dad’s got nothing to do with it.”
Q. What sort of manner did he say that in, when he said “Dad’s got nothing to do with it”?
A. He was quite serious and I realised that it was not something that I should pursue.
Q. Do I take it that you didn’t pursue that?
A. No I didn’t.