A young man’s disturbed obsession with his ex-girlfriend in Omaha, Nebraska in 1978 ended with two people dead, one an 11-month-old child and the young man himself, 12 years later found dead in his cell from an overdose of antipsychotic medication. 25-year-old Steven Harper was a troubled individual who could not handle rejection. His hurt feelings combined with an intense love for his ex-girlfriend produced a dangerous fixation he continued year after year, emerging as anger, violence, and a desire for revenge.

Steven Harper grew up in Omaha enjoying a happy and balanced childhood. When he was 9-years-old, however, while playing with friends and setting fire to grass snakes, Steven accidentally set fire to himself. He suffered severe burns and spent month after month in the hospital enduring numerous operations to try and repair the damage. A confident child changed into a boy all too aware of his injuries, fearing how he would be accepted by his peers and that he would never find a girlfriend. He was an intelligent boy and dedicated his energies to his studies.

Steven Harper

Steven Harper

Sandra Betten was a girl he had known at school and when her marriage failed, the pair became close in 1973 when Steven was 20-years-old and started a relationship. Steven Harper fell madly in love. It was a relationship that didn’t last with Harper due to start veterinary studies and Sandra wanting to settle down and start a family. They separated and Sandra went on to marry Duane Johnson in January 1975, much to Steven Harper’s dismay. He desperately tried to persuade Sandra to annul her marriage to Duane and return to him, something Sandra did not wish to do.

The rejection Steven Harper felt quickly turned to anger directed at both Sandra and Duane Johnson, with his court documents from 1988 stating, “Harper threatened to kill both her and her husband.”  He was angry Sandra didn’t want him anymore and angry that Duane had the woman he wanted to be with.

On the night of 21 June 1975, five months after their marriage, Sandra and Duane Johnson were approached by Steven Harper outside Sandra’s mother’s home. Carrying a shotgun, Harper shot directly at Duane Johnson, missing and sending him running for his life. Sandra’s brother, also at the house and wishing to protect his sister, stepped forward telling Harper to put his gun down. In response, Harper shot him twice also turning to shoot Sandra’s mother in the face. Both survived the shootings but it was a level of violence from Steven Harper that terrified the entire family. Harper went on the run. He spent a year in Oklahoma, trying to stay under the radar knowing he was a wanted man.

Steven Harper was eventually arrested and charged with attempted murder after he was caught through a routine traffic stop. He was jailed for one to five years after being convicted of shooting with intent to kill, wound, or maim. An unremarkable prisoner, he kept his head down in prison achieving parole and returning to the Omaha area in November 1977. After his release, Steven Harper returned to live with his parents and continued following his passion for animals and veterinary medicine. He secured a post as a research assistant at the Eppley Research Institute in Omaha in preparation for college. Here he helped with experiments on rats, studying how different chemical substances related to cancer research affected them. This also provided him with knowledge and access to a range of drugs. Drugs that when ingested by humans could be deadly.


Recounted by Carol Anne Davis in her book on men and woman who turn criminal ‘Masking Evil‘, on 9 September 1978, Sandra and Duane Johnson were at home with their 2-year-old daughter Sherry and 3-month-old son Michael. During breakfast, Sandra noticed the milk from the fridge didn’t taste right and disposed of it down the kitchen sink. By mid-morning, both Duane Johnson and young Sherry had begun vomiting and feeling very ill. That afternoon, Sandra’s sister Sallie and her husband Bruce Shelton visited their home with their 11-month-old son Chad Shelton. All drank lemonade from the fridge, the same lemonade Duane and taken some hours earlier. Soon all the Shelton family had become very unwell. Over the next few days, various members of the family had been taken into hospital such was the extent of their illness. 11-month-old Chad Shelton’s little body could not withstand his illness and he died on 14 September 1978.

Duane Johnson also succumbed to his condition, dying an agonizing death through uncontrollable internal bleeding. The autopsies carried out on both bodies suggested a chemical toxin had caused their deaths. The chemical used was Dimethylnitrosamine (DMN), a toxin which interrupts the human body’s ability to clot blood correctly alongside causing devastating damage to the liver.

Police immediately took a closer look at Steven Harper with his history against the Johnson family.  At his home police found a range of chemicals including two empty vials of Dimethylnitrosamine and evidence he had taken rats home from the lab he worked at in order to conduct his own experiments. They also discovered that the family dog and cat had recently died from unexpected, sudden and painful deaths by suspected poisoning causing uncontrollable internal bleeding.


Duane Johnson and his nephew Chad Shelton died as result of poisoning by Steven Harper.

Steven Harper was arrested and charged with two counts of first degree murder and three counts of poisoning with intent to kill, wound or maim in relation to the other family members who had suffered due to his actions. He eventually confessed during questioning by police, confirming he had stolen cancer-inducing drugs from his employer and after watching the Johnson household for weeks to establish their routines, had broken in and laced the milk and lemonade in the family’s fridge with chemical toxins with intent to cause the family harm.

Before his trial started in Omaha in September 1978, Steven Harper tried to kill himself twice, both times being returned to jail after treatment. At trial, his defense suggested alternative ways Duane Johnson may have been poisoned including through his job as a truck driver or through a severe case of food poisoning. The prosecution painted a clear picture of an angry and rejected Steven Harper using his access to deadly chemicals through his employment to plan and carry out an organised attack on the Johnson family. Bolstering their case was a former inmate Harper had served time with at Nebraska Penal Complex who testified that Harper had confessed to him he had tried to murder his ex-girlfriend to ensure no one else could have her if he couldn’t. The jury was convinced and found him guilty on all counts ensuring he received a death sentence.

Steven Harper spent the following 12 years in prison, filing appeal after appeal through his lawyers in attempts to get his sentence reduced or overturned. All failed and it became clear that he was not going achieve his freedom. Steven Harper was taking regular antipsychotic medications in an attempt to control his mental health. In 1990 he began secretly storing his medication, indicating to prison staff he had swallowed his pills when in fact he was keeping them, building up a stockpile.

On 6 December 1990 Steven Harper was found dead in his cell from an overdose. His death officially ruled a suicide. Harper had finally succeeded in taking his own life. His actions in 1978 have left devastating effects on the Johnson and Shelton families. Those who did survive his poisoning have been left with long-term health damage and nothing can bring Duane Johnson and little Chad Shelton back. One man’s revenge targeting his ex-girlfriend ended in him taking the lives of two of her family members and eventually, his own.