Markham Duff-Smith ordered the murders of the Wanstrath family: Prosecuting Evil With Kelly Siegler investigates

Mugshot of Markham Duff-Smith
Markham Duff-Smith was executed for his savage crimes. Pic credit: TX Dept. of Criminal Justice

Prosecuting Evil With Kelly Siegler is examining the horrific murders of the Wanstrath family, who were shot dead in their Houston, Texas, home by Allen Wayne Janecka at the behest of Markham Duff-Smith.

In 1979, a community in west Houston was shocked when the bodies of John and Diana Wanstrath and their 14-month-old baby boy, Kevin, were found shot dead in their home.

Baby Kevin had been shot in the head as he sat in his crib surrounded by stuffed animals. The cops initially assumed it was a murder-suicide, and the Harris County medical examiner’s office eventually concluded that Diana had killed her husband and son before turning the gun on herself.

However, the cops never found a gun at the house. Houston police homicide detective Johnny Bonds never accepted the ruling and worked hard to find the truth.

Bonds eventually gathered enough evidence to conclude that Diana’s adoptive brother, Markham Duff-Smith, had masterminded the murders in order to claim their estate worth nearly $1 million.

Duff-Smith had hired Allen Janecka to be the hitman. A third man, Walter Waldhauser, had acted as a middleman communicating details from Duff-Smith to gunman Janecka.

Wanstrath murders led to charges against Markham Duff-Smith for Gertrude Duff-Smith Zabolio murder

This case led the police to re-investigate the death of Duff-Smith’s adoptive mother, Gertrude Duff-Smith Zabolio, who was strangled to death in her home in the Houston neighborhood of River Oaks on October 15, 1975. At the time, Gertrude Duff-Smith Zabolio’s murder was ruled a suicide.

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However, the cops subsequently reclassified the death as a homicide. Again, working through Waldhauser, Duff-Smith had ordered Janecka to strangle his mother so he could claim an inheritance of about $100,000. He offered $10,000 of that amount to Janecka.

The victim’s husband, Dow Zabolio, was also supposed to be murdered, but he was away on a business trip to Austria.

The cops believe Duff-Smith burned through his inheritance very quickly, and by 1979, he sought out Janecka, once again, to kill Diana Wanstrath and her family.

Janecka and Waldhauser both turned on Duff-Smith, agreeing to testify against him. Janecka admitted to the killings, once telling officers that he “took care of the little one.”

Allen Janecka and Markham Duff-Smith executed for murder

In July 2003, Janecka was executed by lethal injection, having spent 22 years on death row. His last words were, “For many years, I have done things my way, which has caused a lot of pain to me, my family and many others. Today, I have come to realize that for peace and happiness, one has to do things God’s way.”

Duff-Smith was charged but not convicted of the Wanstrath killings. However, he was sentenced to death for the capital murder of his mother. He was executed by lethal injection on June 29, 1993.

The killer’s last words appeared to be an admission of guilt for all murders. He said, “I am the sinner of all sinners. I was responsible for the ’75 and ’79 cases.” But he also added, “My trial was not just; it was not fair; they lied against me.”

Waldhauser pleaded guilty to his role in the murders and was given a 30-year sentence.

Prosecuting Evil With Kelly Siegler airs Saturdays at 8/7c on Oxygen.

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