More on serotonin and violence

This is in response to Sashi's comments on the post - Serotonin, mood and violence.
Serotonin is widely present in the other tissues like gastro intestinal tract, blood etc. There is poor correlation between its concentration in the peripheral blood and within the brain. Hence there is no point in correlating these two. Further, serotonin from peripheral blood does not cross the blood brain barrier to enter the brain.
But tryptophan, the amino acid precursor of serotonin does cross the blood brain barrier to enter the brain. May of us have a habit of drinking milk at bed time. Milk is a rich source of amino acids including tryptophan. Could this practice help to improve our sleep ? I am not aware of any studies that have tried to influence our mood states using dietary modification.
Suicide bombers are indoctrinated into certain beliefs that justify their acts. Such indoctrinations can change the personality of a person and make him perform the crime. Without evidence it is difficult to say whether suicide bombers have low serotonin in their brains, but it is a likely possibility. But we have not reached a stage where we can use the serotonin levels or any other biological markers to accurately identify people who are likely to commit suicide, violent crimes etc. This may be possible in future with further advances in our understanding of the causes of human behavior and the development of refined techniques to measure neural correlates of such behaviors.