Intercourse between the two men

两个男人间的性交
was most likely the unsub's trigger.

可能是嫌犯的触发点
Immediately after copulation,

性交后结束后
the male's serotonin levels drop.

男性体内的血清素含量会降低
The high is achieved during sex.

而在性爱过程中会达到最高值
That rapid change can manifest itself in extreme depression

那种急速的变化可能导致极度抑郁
and low self-esteem.

和自信心低落
Combined with an apparent belief

加上他坚定地认为
that acting on his attraction towards other men is wrong,

喜欢男人是一种罪恶的行为
this state causes the unsub to lash out violently at those he's with.

这种状态会导致嫌犯对身边的人施暴
As his levels normalize,

等血清素水平恢复正常
he begins to feel remorse for what he's done

他会开始悔恨自己的行为