Dr. Brett Morton was a psychologist in the episode "Conscience" whose son was kidnapped and murdered by his thirteen-year-old neighbor, Jake O'Hara.
History
Morton wrote papers on the subject of child sociopathy. In these papers, he cited that their condition cannot be cured and measures should be taken to prevent these children from committing inevitable acts of violence.
During Jake's trial, Morton initially requests leniency for him, but after information comes to light that he has psychopathic tendencies and that he will be released from prison by the time he is eighteen, Morton regrets his decision and shoots Jake in the courthouse. He then uses his expertise as a psychologist to try and convince the court he had post-traumatic stress disorder at the time. He was subsequently acquitted of the murder.
At the end of the episode, Morton confesses to Stabler and Novak that he was guilty over his request for leniency for Jake, that he feared he would kill again after his release, and that he planned to shoot Jake in the courthouse after he found out he was a sociopath. Stabler and Novak confront Morton for his "manipulation" towards the court, like Jake. Morton agrees with Stabler, but points out one thing that distinguished him from Jake: that he would have killed again whilst the psychologist himself will not.