This is idiocy.
Everyone has a variant of MAO A.
Some variants are correlated with violent behavior under certain comorbidities.
That’s all.
The original work done by Bruner to show that the loss of MAO A was correlated with an increased aggressive behavior was not associated with murderous behavior.
And that is with a total loss of MAO A function.
The jury was fooled by a large impressive sounding word. I guess if they’d proved he had cyclic AMP or a sulfur containing amino acid they’d come to the same conclusion. I know of researchers that have more bullshit in them than a West Texas feedlot.