Dr. Death. It was a fitting nickname for the tall gentleman with a spectral complexion who haunted the corridors of the Dallas County Courthouse  in the 1980s.
Summoned by prosecutors to testify in more than 100 capital murder cases, Dr. James Grigson  delivered his diagnosis with creepy Marcus Welby -ish solemnity. Sometimes without having met a defendant, he'd confirm what prosecutors needed jurors to hear - that the miscreant posed a continuing threat to society.
He checked an important box for prosecutors who, under Texas' death penalty law, had to prove to juries that the "future dangerousness" of a defendant warranted execution. Without his testimony, the cases would have been run-of-the-mill murders with ordinary prison sentences.