Knorr was born Theresa Jimmie Francine Cross on March 14, 1946 in Sacramento, California. She was the youngest of two daughters born to Swannie Gay (née Myers) and James “Jim” Cross. Swannie Cross had two children, a son and a daughter, from a previous marriage. Theresa’s father Jim worked as an assistant cheese maker at a local dairy. He eventually saved up enough money to buy a home in Rio Linda, California. In the late 1950s, Jim Cross was diagnosed with Parkinson’s disease which forced him to quit his job. He developed depression and reportedly took his frustrations and anger out on his family. Swannie Cross kept the family afloat financially. Theresa was reportedly very close to her mother and was devastated when she died of congestive heart failure in March 1961. Thereafter, Jim Cross was unable to afford to keep the family home and sold it soon after Swannie’s death.
On September 29, 1962, 16-year-old Theresa married Clifford Clyde Sanders, a man five years her senior whom she had met a few months prior. After the marriage, Theresa dropped out of high school and became pregnant. On July 16, 1963, she gave birth to her first child, Howard Clyde Sanders. Sanders’ and Theresa’s marriage was rocky as Theresa was possessive and repeatedly accused Sanders of infidelity. The couple argued frequently and on June 22, 1964, Theresa claimed that Sanders had punched her in the face during one such argument. Theresa reported the incident to police but refused to press charges against Sanders. The assault charges were subsequently dropped.
After the birth of Sheila, Theresa began drinking heavily. She regularly drank at the local American Legion Hall where she met Estelle Lee Thornsberry, a disabled United States Army veteran. The two began a relationship and eventually moved in together. During the relationship, Theresa would routinely leave her children with Thornsberry while she went out drinking. Thornsberry began to question Theresa when she stayed out for days at a time and ended the relationship a few months later after he discovered that she was having an affair with his best friend. Shortly after the relationship with Thornsberry ended, Theresa met and began a relationship with a United States Marine private named Robert Knorr. She soon became pregnant and the couple married on July 9, 1966.
Knorr’s third child, Suesan Marline Knorr, was born on September 27, 1966. The couple had three more children: William Robert Knorr (born September 15, 1967), Robert Wallace Knorr, Jr. (born December 31, 1968) and Theresa Marie “Terry” Knorr (born August 5, 1970, died December 8, 2011), whom Theresa named after herself. Theresa and Robert Knorr’s marriage began to deteriorate after Theresa began accusing her husband of having affairs. Fed up with Theresa’s constant accusations, Robert Knorr left her in June 1969 and was granted a divorce in 1970. After the divorce, Robert Knorr attempted to see his children but Theresa prevented him from doing so.
Theresa Knorr would go on to marry two more times; in 1971, she married railroad worker Ronald Pulliam. That marriage began to fall apart when Knorr began leaving her children with Pulliam while she stayed out all night drinking and partying. Pulliam divorced Knorr in 1972 after he became convinced that Knorr was having an extra-marital affair. Her fourth and final marriage was to Sacramento Union copy editor Chester “Chet” Harris, whom she married in August 1976. Knorr’s daughter Suesan grew close to Harris which made Knorr jealous. She filed for divorce from Harris in November 1976 after she reportedly found out that Harris enjoyed taking consensual nude photographs of women.
Knorr was physically, verbally, and psychologically abusive towards her children. After her fourth divorce, Knorr’s abusive behaviour escalated as did her alcoholism. Around this time, Knorr gained a tremendous amount of weight and became quick tempered and reclusive. She disconnected the home phone and would not allow the children to have visitors. Knorr and her children lived in Orangevale, California for many years before moving into a two-bedroom apartment in Sacramento (Knorr’s eldest son Howard reportedly left the home before the family moved to Sacramento). According to neighbours, the apartment was filthy and smelled of urine. Neighbours also noticed that Knorr never allowed her children go outside and that the children seemed fearful, nervous and high strung. For years, Knorr abused and tortured her children in various ways including burning them with cigarettes, throwing knives at them, forced feedings and beatings. She made her children hold each other down while she beat and tortured them. In one instance, she held a pistol to her youngest daughter Terry’s head and threatened to kill her.
Knorr primarily focused her anger and abuse on her two eldest daughters, Suesan and Sheila. In an interview with Knorr’s surviving daughter Terry, she said her mother resented that Suesan and Sheila were maturing and blossoming into attractive young women while she faced the prospect of growing old and losing her looks. Knorr also believed that her fourth husband, Chet Harris, had turned Suesan into a witch. Because of this belief, Suesan received the worst of Knorr’s abuse. After one severe beating, Suesan ran away from home. She was picked up by police and placed in a psychiatric hospital where she told staff of the abuse at the hands of her mother. Knorr denied the abuse claims and told the hospital staff that Suesan had mental issues. Authorities did not investigate the matter further and released Suesan back into her mother’s custody. Knorr punished Suesan for running away by beating her while wearing a pair of leather gloves. She also forced her other children to take turns beating Suesan. In the subsequent weeks, Knorr handcuffed Suesan to her bed and ordered her other children to stand watch over her. Knorr refused to let Suesan leave the house and forced her to drop out of school. Knorr also pulled her other children out of school, and most of them never advanced past the eighth grade.
While Suesan was unconscious, Knorr ordered her then 15-year-old son Robert to remove the bullet with an X-Acto knife. Suesan awoke the following day in immense pain. Over the following days, she developed septicemia and became delirious. Knorr attempted to treat her with ibuprofen and antibiotics. The treatments were ineffective and Suesan’s condition continued to decline. On July 16, 1984, Knorr packed all of Suesan’s belongings in trash bags and, after binding Suesan’s arms and legs and placing duct tape over her mouth, ordered her sons Robert and William to put Suesan in their car. They drove her to Squaw Valley where Robert and William placed her on the side of the road on top of the bags containing her belongings. Knorr then doused Suesan and the bags in gasoline and lit the girl on fire. Suesan’s still smoldering body was found the following day. An autopsy determined that she was still alive when she was lit on fire. Due to the state of the remains, a positive identification was never made and Suesan was classified as Jane Doe #4873/84.
Following Suesan’s death, Theresa Knorr began directing the majority of her anger and abuse towards her daughter Sheila. In May 1985, Knorr forced Sheila into prostitution to support the family. Knorr did not work and received money from the state of California. Knorr was initially pleased with this arrangement due to the large amounts of money Sheila was earning and allowed Sheila to leave the house whenever she pleased. After a few weeks, Knorr became angry and accused Sheila of being pregnant and contracting a sexually transmitted disease which Knorr claimed she caught from Sheila via a toilet seat. Sheila initially denied the accusations. So Knorr beat her, hog tied her and locked her in a hot closet with no ventilation. Knorr forbade her other children to give Sheila food or water or to open the door to the closet. Terry Knorr disobeyed her mother and gave Sheila a beer. Terry Knorr later said, “She [Theresa] wanted Sheila to confess. That was mother’s way. Beat them until they confess.” To end the punishment, Sheila confessed to being pregnant and having an STD but Knorr would not let her out of the closet claiming that Sheila was lying. Sheila died three days later, on June 21, 1985, of dehydration and starvation. Knorr left Sheila’s body in the closet for an additional three days before discovering that Sheila was dead. Once again, Knorr ordered her sons William and Robert to dispose of Sheila’s body which had begun to decompose causing an odorous smell that filled the apartment. The boys placed Sheila’s body in a cardboard box which they disposed of near the airport in Truckee, California. Sheila’s body was discovered a few hours after it had been disposed of but was never positively identified and was classified as Jane Doe #6607-85.
Even though Sheila’s body had been removed from the closet, the smell of decomposition still lingered in the apartment. Knorr became concerned that the smell and physical evidence in the closet could implicate her in Sheila’s death. On September 29, 1986, Knorr moved the family’s belongings out of the home and ordered her youngest daughter Terry to burn down the apartment in an effort to destroy any physical evidence. During the night, Terry Knorr dumped three containers of lighter fluid on the apartment floor and set it on fire. The fire did little damage as neighbours quickly reported the fire before it spread. The closet in which Sheila died was not damaged. After Knorr’s arrest, investigators were able to remove the subfloor from the closet to test it for physical evidence. After leaving the Sacramento apartment, Knorr went into hiding. Her surviving children, who were by then of legal age, severed their ties with their mother. Knorr’s youngest child, 16-year-old Terry, also left her mother’s care and used Sheila’s identification card to pass herself off as a legal adult. The only child to remain with Knorr was Robert, Jr. who was then 19 years old. Knorr and Robert, Jr. moved to Las Vegas and attempted to keep a low profile. In November 1991, Robert Knorr, Jr. was arrested after he fatally shot a bartender in a Las Vegas bar during an attempted robbery. He was sentenced to 16 years in prison. Shortly after Robert, Jr.’s arrest, Knorr left Las Vegas and relocated to Salt Lake City.
After escaping from her mother, Terry Knorr attempted to report her sisters’ murders to the Utah police but they dismissed her stories as fiction as did a therapist she visited. On October 28, 1993, Terry Knorr contacted America’s Most Wanted, who asked her to contact detectives in Placer County, California (the county in which Suesan’s body was found) who took her claims seriously and followed up with an investigation. The detectives linked the two Jane Does found in the area in 1984 and 1985 to Terry Knorr’s detailed stories of her sisters’ deaths and concluded that she was telling the truth. Knorr’s son William was arrested on November 4, 1993 in Woodland, California where he had been living and working. Robert Knorr, Jr. was charged with his sisters’ murders while he was serving a 16-year sentence in an Ely, Nevada prison for the 1991 murder of a Las Vegas bartender. On November 10, 1993, Theresa Knorr was arrested at her home in Salt Lake City. At the time of her arrest, Knorr was using her maiden name of “Cross” and was working as a caretaker for her landlord’s 86-year-old mother.
On November 15, 1993, 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. Knorr initially pled not guilty but then made a deal with the prosecution after learning that her son Robert, Jr. agreed to testify against her in exchange for a reduced sentence. She pleaded guilty on the condition that she be spared the death penalty. On October 17, 1995, Knorr was sentenced to two consecutive life sentences. She is incarcerated at California Institution for Women in Chino, California. She will be eligible for parole in 2027. William Knorr was sentenced to probation and ordered to undergo therapy for participating in his sister Sheila’s murder. In exchange for his testimony, the prosecution dropped all charges against Robert Knorr, Jr. save for one count of being an accessory-after-the-fact in relation to Sheila’s murder. Robert Knorr, Jr. pleaded guilty to the charge and was sentenced to three years in prison which was served concurrently with his 16-year sentence for the unrelated 1991 murder of a Las Vegas bartender.
Following Knorr’s arrest, police decided to reopen the murder case of her sister, Rosemary Norris. Norris was found strangled at the end of a dead end road in Placer County in 1983 after she went grocery shopping in Sacramento. Police later determined that Knorr was not involved in Norris’ death. After moving out of her mother’s home, Terry Knorr married twice and eventually moved to Sandy, Utah, where she lived with her second husband. She worked as a grocery store cashier in the same neighbourhood where her mother also lived and worked before her arrest. Theresa and Terry apparently did not know they lived in close proximity and had no contact. Terry Knorr died in Saint Joseph, Missouri, of a heart attack, on December 8, 2011. She was 41 years old.
At the age of 71 Theresa Knorr is still alive and has so far served 22 years of her sentence in California Institution for Women in Chino, California.