Dean Cottle testified that Laniet said she was having an incestuous relationship with her father.

A change to Dean Cottle's initial statement was the key 'suppressed evidence' from the first trial that Joe Karam used in order to get a retrial and the key piece of Defence 'evidence' incriminating Robin and by implication absolving David.  Cottle's testimony was omitted from the first trial because the judge considered Dean Cottle to be an unreliable witness, a judgment which Cottle has reinforced several times with the following:

1. He failed to appear for the first trial and an arrest warrant was issued
2. He changed his testimony following the first trial
3. He failed to appear for the retrial and an arrest warrant was issued

The supposed incestuous relationship was used in the retrial to give a motive for Robin to commit the murders.

Not only is Dean Cottle an unreliable witness but considerable doubt has also been cast on Laniet's reliability as a witness as follows:

Testimony that Robin and Laniet had a normal father daughter relationship.

1/ Robin shared a school house 30 miles down the coast from Dunedin with two people one was his daughter Laniet and the other Laniets friend Kyle Cunningham, he said at trial that Laniet and her father had a normal father daughter relationship.

2/ Clifford Williamson knew Robin Bain for a year or two before his death. His children attended the Taieri Beach School. The witness provided Robin Bain with a house at Taieri Beach for the latter’s week-day use, during a period when the school house was unavailable. He also went on a school camp with both Robin and Laniet, approximately one month before their deaths. Mr Williamson’s evidence covers four matters. During the school camp he observed interaction between father and daughter over a number of days. He considered them to have “a normal relationship”.

3/ A former friend of Laniet Bain, name suppressed, told the court Laniet wanted to get away from her pot-smoking lifestyle when she moved out to her father's school house in Taieri. She said Laniet got on well with her father but was a disappointment to her mother and they fought a lot.

Physical education teacher Paul Hewson was at Bayfield High School as a sports co-ordinator in 1992 when Arawa Bain was the head girl at the school. He spoke to Laniet most often and took her class for physical education and sometimes their study class. From early on he was surprised how open she was. She said she was raped in Papua New Guinea and the resulting baby was black. The story seemed to change when she later said she had had an abortion. "I didn't know what to make of it,'' he said On one occasion she said she had attempted to kill herself by slashing her wrists but he had not been able to see any scarring on them.  She had said her sister Arawa had saved her otherwise she would have died. When he saw Laniet after she left school she told him she was working as a prostitute and she was going to move in with her father at Taieri Mouth.

Laniet Bain told a fellow prostitute she had been sexually abused by her father in Papua New Guinea and that the baby she had there was his. The woman, who now lives in Christchurch, said Laniet told her the baby was white and she had seen a photograph of a white baby in Laniet's room. Previous witnesses have told the David Bain retrial Laniet claimed she had a black-skinned baby after being raped in PNG. The former prostitute was one of two witnesses, both granted name suppression, who gave evidence at trial in 2009 about being told by Laniet she was being sexually abused by father Robin.  

Laniet told conflicting stories none of which could be substantiated. Laniet made claims that she had been raped and had a black baby, raped and had a white baby, had an abortion, attempted suicide, but there is not one shred of evidence that can substantiate these claims. Even David is on record as saying Laniet had no baby, and the extended family say she had no baby. In short there is no evidence for black babies, white babies, abortions, rapes or suicide bids.

There is only one explanation for all of this and that is Laniet was for some emotional reason telling untruths! All in all, Laniet's supposed assertions to friends and acquaintances have little credibility. They have the sound of a cry for help from a young girl desperately needing the normal attention and affection of a loving family. The Bain's were anything but normal.  But once installed in peoples minds the incest stories took on a life of their own promoted by Joe Karam's insistence on their relevance to exonerating David Bain.

It must be noted that if Laniet was having an incestuous relationship with her father then David Bain would be in a position to personally testify, and his testimonial would once and for all put an end to the matter for the Defence.  That in fact happened between David and his first lawyer, Michael Guest:

David Bains lawyer from the first trial said after David was acquitted in the 2009 trial that he had fought to have the incest allegations heard through the first Privy Council hearing in 1996. However in an interview with radio NZ regarding the incest allegations, his exact words were "personally I am sad that it was used, I personally don’t believe what Laniet said".

The interviewer then asked Michael Guest "so you don’t believe that Laniet was having an incestuous relationship with her father?" Michael Guests exact reply was "I personally don’t". The interviewer then asked Guest “What do you base that opinion on?”. Michael Guest replied "David himself said he simply didn’t believe that was going on, David said he had never seen anything like that at all".  Michael Guest then went on and said "I actually don’t believe having looked at all the new evidence that in fact Laniet was telling the truth".

It’s interesting that David told his lawyer Michael Guest that he did not believe his father was having incest with his sister in yet he sat back in court and let strangers drag his fathers good name through the mud in order to help him get off.