Crime Library: Criminal Minds and Methods

The Trailside Killer of San Francisco


An individual identifying himself as Mark McDermand called the number that evening, October 24. He said he would consider giving himself up, but he had some things to do first.  He called again two days later, describing details about the killings.  He said he had tried to kill his mother and brother quickly, but he'd miscalculated with Edwin and had to shoot him five or six times.  His motive was to stop Edwin from hurting others and to prevent his mother from realizing that he'd killed Edwin.  He then agreed to turn himself in the following day. 

When he approached the police, McDermand was wearing a belt with a .38-caliber revolver in it.  He also had a set of thumb cuffs and three speed loaders.  In his car was a .22-caliber pistol, a .12-gauge shotgun, ammunition, a metal box containing numerous hypodermic syringes, and some vials of insulin.  Mark had diabetes.

When the investigation was complete, the police thought they had a good sense of the story.  Edwin had a record of acting strangely and been diagnosed with schizophrenia.  He deteriorated rapidly.  Mark became impatient, referring to him as "It" or "the Thing." On one or more occasion during the six-month period prior to the murders, he had confided to a friend in a dejected manner that he didn't know what would become of his brother once their mother was gone, and that someday he "would put 'it' out of its misery."

McDermand had borrowed the guns he used in the homicides, and had then prepared himself to go on the run for a number of months.  In his defense, he said that he had acted out of diminished capacity and indicated that, like his brother and mother, he suffered from schizophrenia.  There was little dispute that Edwin's mental state was disorganized, and evidence was offered that Mark, too, had experienced headaches and blackouts.  He claimed he could not even remember the murders, or when he did, he recalled a number of different versions.

The jury nevertheless found Mark McDermand guilty of two counts of first-degree murder, and he received the death penalty.  Yet his potential part in the trailside murders was quickly resolved: none of his weapons matched the bullets used on the two victims who'd been shot.  And, most telling, after he was in custody, the murders continued.  The next discovery was horrifying.


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