Oct. 20, 1993: A woman working the tip lines for the popular show America?s Most Wanted receives a call from a tearful young woman. They?ve just aired a segment about two unidentified murder victims, both young women in their late teens or early 20s, whose cases had gone cold. The first victim was found off a rural road in Placer County, California, in 1985. She had been burned almost beyond recognition, and had duct tape covering her mouth and around her wrists. In her back was a long gash, as though from a knife.
A few of her belongings, as well as several diapers, were found around her remains, leading police to worry that she had an infant who was now missing and possibly in danger. An autopsy would reveal that she had been alive when she was set on fire. But police couldn?t identify her, and she didn?t match anyone who had been reported missing.
The second victim, found a year later, had been hog-tied, stuffed into a large popcorn-cup box, and discarded in Martis Creek Lake, near Truckee, California. Her remains had been too decomposed to identify or determine her cause of death. The only identifying features they could find on her remains were her chipped front teeth. But no one had reported this young woman missing, either, so her case went cold as well.
The woman on the other end of the tip line tells the operator her name is Terry Knorr. She has an incredible story of cruelty to tell, one that is so horrific that for years, no one has believed her.
The two murdered women, she tells the operator, are her older sisters, Suesan and Sheila. Their murderer, she says, was their mother, Theresa Knorr.
Terry ran away from home when she was 15. Living on the streets, battling with mental health issues and addiction, she frequently found herself on the wrong side of the law. Every time she was arrested, she would tell the police about the horror movie that had been her life growing up. Her mother, she tried to tell them, was a monster who had tortured her children and killed two of them. But no one ? not even her therapist ? would believe her.
Until she was put in touch with the Placer County Sheriff?s Department, who recognized that many of the details Terry told them fit with their unsolved Jane Doe. At the Nevada County Sheriff?s Department they recognized the story as well. Finally, someone believed her.
Theresa Cross had always been a manipulative, controlling person. When she was 16, she dropped out of school to marry Clifford Sanders. While they were married, she gave birth to her first child, Howard. She was described as jealous and controlling of Clifford, constantly accusing him of cheating on her. They fought often, and Clifford punched her on at least one occasion.
Then, on July 6, 1964, they argued again. Clifford announced he was leaving Theresa, who was pregnant with Sheila. She shot him in the back with a .30-.30 rifle as he was walking out the door. The slug lodged in his heart, killing him.
Theresa pled not guilty, claiming self-defense. It worked; she was acquitted.
Now a single mother of two, Theresa began drinking more frequently. She also began a string of relationships. One of which was to a Marine named Robert Knorr, with whom she had four more children: Suesan, Robert, William, and Terry. Robert adopted Howard and Sheila, who changed their last names to Knorr as well.
Once again, Theresa?s heavy drinking, jealousy, and constant accusations of infidelity drove her husband away. He left in 1969 and they divorced in 1970. Robert wanted to remain in contact with his children, but Theresa refused.
She married twice more, and both of those marriages fell apart due to her drinking and jealousy.
After her last divorce, her mental and physical health began to deteriorate. She gained weight and began having paranoid delusions. She took the children out of school, cut off phone service to their home, and wouldn?t let the children go outside.
Always controlling, Theresa began to become more violent and unpredictable. She accused her children of things they had not done, and would beat them for their imaginary actions. Her children describe the weapon she would beat them with: the ?Board of Education,? a 3-foot long board that was about 1 ? thick, with electrical tape wrapped around one end to form a handle. Theresa would make her other children hold their sibling down while she beat them.
Her abuse didn?t stop with beatings, though. She would burn her children with cigarettes, force them to do grueling labor in the heat, deprive them of sleep, and throw knives at them as a ?game.? She once locked Terry in a chest freezer for the supposed crime of telling other people that Theresa didn?t take care of her children.
But the worst of her anger and abuse was directed towards her daughters. She forced the oldest two, Suesan and Sheila, into prostitution. At one point, she became convinced that Suesan was a ?witch? who had cast a spell on her, causing her to gain weight. So, in addition to beating her, Theresa began to force-feed Suesan to make her gain weight. Theresa would make huge pots of macaroni and cheese, adding in hunks of lard, and force Suesan to eat all of it. If Suesan got too full to eat any more, Theresa would force spoonfuls of the food into her mouth. If Suesan vomited, Theresa would make her eat that, too.
Sources differ on what happened next. Some say Suesan ran away; others say she was arrested while walking the street. The important thing is that she was finally able to tell the authorities about her mother?s abuse.
Theresa, of course, denied it. Caseworkers questioned the other children, but with their mother in the room with them. Terrified, the children backed up their mother and denied she ever hit them. Satisfied, DHS closed the case and returned Suesan to her mother?s custody.
Whatever hell Suesan had suffered before was nothing compared to what she would endure after that. Theresa handcuffed her under the dining-room table and gagged her. Theresa continued to beat her and force-feed her. She even enlisted her sons, Robert and William, to participate in beating Suesan (Howard left earlier). This went on for about two years.
Accounts differ as to what happened next. Robert claims Theresa gave Terry, who was a young child, a pistol and told her to hold it on Suesan while Theresa went into another room. Something startled Terry and the gun went off, shooting Suesan in the abdomen.
Terry says that her mother shot Suesan during an argument.
Either way, Suesan was in grave condition.
Rather than call an ambulance, Theresa had the boys carry their sister into the bathroom and put her in the tub. There, Theresa handcuffed her to the soap dish. Over the next couple of weeks, Theresa managed to nurse Suesan back to health.
Once she was well enough to get out of the tub, it was back under the table for Suesan. She begged her mother to just let her go, promising she wouldn?t tell anyone what had happened.
This went on for quite a while, until Theresa eventually relented. But with one condition: Suesan had to let her mother take the bullet out of her body, so there wouldn?t be any evidence Suesan could use against her later.
Desperate for an escape, Suesan agreed. So Theresa fed her daughter antipsychotic drugs and copious amounts of whiskey until she passed out on the kitchen floor. Then, with Terry at her side acting as ?surgeon?s assistant,? Theresa cut into her daughter?s back with an X-acto knife and dug the bullet out. After the surgery was complete, Theresa flushed the bullet down the toilet.
But Suesan never recovered. She woke up in horrific pain. Theresa gave her ibuprofen and antibiotics. Suesan became delusional from infection and pain, and soon slipped into a coma. Theresa insisted Suesan was ?just faking it,? and left her on the kitchen floor, instructing her other children to just step over her unconscious body. As Suesan lost control of her bladder, Theresa just put diapers on her. As Suesan?s body turned yellow from sepsis and jaundice, Theresa claimed it was proof that Suesan was possessed by a demon.
And the only way to exorcise the demon, she believed, was with fire.
So Theresa put duct tape over Suesan?s mouth and bound her wrists with it. She instructed her sons to load Suesan and her few belongings ? including her diapers ? into the trunk of the car. Then they drove out to a secluded area and carried Suesan and her things to a spot just off the road. Theresa ordered her sons to pour gasoline over everything ? including their sister. She then had William light a match, and they drove off, Suesan?s body burning behind them.
With Suesan gone, Theresa?s fury now focused on Sheila. Like she had with Suesan, Theresa began force-feeding Sheila. Once she shoved a spoon into Sheila?s mouth so hard, it chipped her two front teeth.
Then Theresa accused Sheila of getting a venereal disease and passing it on to her through the toilet seat. She beat Sheila and handcuffed her under the table, as she had with Suesan. Sheila was forbidden to use the toilet or even the bathtub.
Theresa continued to beat Sheila, demanding she ?confess? to giving her mother a venereal disease. When that didn?t work, Theresa hog-tied her daughter and shoved her into a broom closet.
She left her there for weeks without food or water. When Sheila would scream and plead to be let out, Theresa would simply turn up the TV to drown her out.
Terry tried sneaking her sister water, but her mother came home before she could. Sheila became delusional, talking about climbing up towards a light. Then she went silent. The last thing any of them heard from the closet was a loud thump. Days later, a horrid, rotting stench came from the closet.
When Theresa finally opened the closet door, Sheila?s decomposing body fell out.
Theresa called in her sons to help dispose of it. Robert brought the biggest box he could find, a popcorn-cup box from the theater where he worked. They wrapped Sheila?s remains in bed linens and stuffed her inside the box, then loaded her into the trunk of the car.
Terry was ordered to clean the closet where her sister had died.
Meanwhile, Theresa and her sons drove to a secluded spot to dump and burn Sheila?s remains, as they had with Suesan. But before they could unload the box, a police officer pulled up behind them. Theresa was able to talk her way out of any suspicion, claiming her boys had needed to use the bathroom. Despite smelling the stench of decomposition, the police officer simply told her to move along.
So they drove to Martis Creek Lake and dumped the box with Sheila?s remains. They didn?t stick around to set it on fire for fear of getting caught.
Terry?s recollections stunned the police officers. They could scarcely imagine the level of cruelty she had described. But the details she provided aligned too neatly with the crime scenes to be dismissed. They answered questions that had baffled the investigators, such as why there were diapers near the Placer County Jane Doe, and what the gash on her back had been caused by.
So in November 1993, arrest warrants were issued for William, Robert, and Theresa Knorr. Robert was easily found: he was in a Nevada prison for shooting and killing a bartender in a robbery two years earlier. William was living and working in Woodland, California.
Theresa, however, was harder to apprehend. Using her maiden name, she had moved to Salt Lake City, Utah, and was working as a caretaker for an elderly woman. Authorities caught her just in time; she had withdrawn $4,000 from her bank account and notified her employer she was leaving town. When authorities took her into custody, she already had her bags packed.
In exchange for his testimony, all charges against Robert were dropped except one count of accessory after the fact. He pled guilty and was sentenced to three years, to be served concurrently with his previous sentence.
William, in exchange for his testimony, was sentenced to probation and mandatory therapy.
Theresa Knorr was charged with two counts of murder, two counts of conspiracy to commit murder, and two special circumstances charges: multiple murder and murder by torture. At first she pled not guilty, but once she learned of her sons? plea agreements to testify against her, she changed her plea to guilty to avoid the death penalty. On Oct. 17, 1995, she was sentenced to two consecutive life sentences. She is currently serving her sentence in the California Institution for Women in Chino, California. She will be eligible for parole in 2027, when she?ll be 81.
Robert served his sentence and was released in 2013.
Today William works, has a family, and enjoys what he calls a ?normal life.? He shared his story on the TV show Evil Lives Here in 2019.
Terry continued to share her story even after her mother?s arrest, appearing on numerous true-crime TV shows, most notably Cold Case Files, until her death from heart failure in 2011. She was 41.