Initial reports shortly after the crash from police and Ms O'Brien's former partner indicated Ms O'Brien might have been texting while driving. However, this could not be proved in the court case which followed her death.
Mr Bain said there were a combination of elements which contributed to Ms O'Brien's death, which did not include the notion of texting. She had not been wearing her seatbelt and it is believed she was reaching around to the back to pick up one of the children's favourite toys from the floor.
Ms O'Brien was also driving on smooth tyres that were under-inflated and a space saver which was seen smoking moments before the crash.
Mr Bain said this was a ''tragic accident which has resulted in the death of a young woman who was a devoted mother''.
''There is the combination of events ... which sadly resulted in a momentary period of time where it seems she has unplugged her seat belt and leaned into the back seat to retrieve a toy for a child and lost control of the vehicle, which was contributed to by the poor state of the tyres.''
Mr Bain said Ms O'Brien's mother was very upset at the treatment of her daughter in the days following her death.
''It is sad that the family have had to suffer to 'persecution' as described by Mrs O'Brien which has been based on the wrong information and wrong conclusions,'' Mr Bain said.
''One cannot imagine the hurt that this would cause the families and it is hoped that these findings will provide some comfort and enable them to remember their daughter for the devoted mother that she was.''
Ms O'Brien's cause of death was severe head and neck injuries as a result of a motor vehicle crash.