DALLAS -- A successful Dallas businessman who tried to stab his sleeping wife before fatally stabbing himself last month was found to have traces of a drug used to treat insomnia in his bloodstream, police told NBCDFW.com.

The autopsy report from the Dallas County Medical Examiner's Office shows that 50-year-old John "Rod" Steele had .05 milligrams of zolpidem in his system.

According to the U.S. Food and Drug Administration, zolpidem, which is sold under several different names, is used in adults for short-term treatment of insomnia.

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Possible serious side effects can include “more outgoing or aggressive behavior than normal, confusion, agitation, hallucinations, worsening of depression, and suicidal thoughts or actions.”

In the aftermath of Steele’s July 11 death, friends and neighbors told NBC 5 he was taking prescription pills because he had trouble sleeping.

He had no prior history of violence. He taught Sunday school and Bible study at Highland Park United Methodist Church.

The husband and father of two also sat on the boards of two Dallas area banks.

Steele's family had a note on the door of their Highland Park home asking for privacy.

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