Brookie told the jury they may come to the question of manslaughter for the accused, which Justice Moore will direct them on tomorrow.
But, he continued, if any of the jurors were unsure about the Crown's case then they must find the accused not guilty of murder.
"You know, I'm just not sure about this. I have doubts that I just can't dismiss," he said some of the jurors may think.
If a not guilty verdict for murder was returned, Brookie said, then the jury shouldn't feel as if they haven't delivered justice.
"You haven't failed to deliver on the expectations of those who have, long ago, made up their misinformed views about this case."
Grace Millane murder trial: 'It was an accidental death' - defence