While Tinning was convicted on only one count of murder, authorities suspect she killed all nine of her children between 1967 and 1985. None of them lived past the age of four. Experts believe Tinning's is one of earliest documented cases of what was then known as Munchausen syndrome by proxy. Today, experts refer to the syndrome as factitious disorder imposed on another, or FDIA. According to the Cleveland Clinic, FDIA is "a mental illness in which a person acts as if an individual he or she is caring for has a physical or mental illness when the person is not really sick."
But before it became a fascination in pop culture, even before Munchausen syndrome by proxy was described in medical literature in 1970, there was the devastating case of the Tinning family. In the early 70's Marybeth Tinning and her husband Joseph lived in Schenectady, NY where she worked as a school bus driver and waitress. According to CBS News, the three children they had at that time — aged 8 days old, 2 years old and 4 years old — all died within a two-month span in 1972. The causes of death for the two older children were attributed to cardiac arrest and seizures. The infant was believed to have died of acute meningitis.
In 1973, the couple's two-week old infant also died. Authorities attributed that death to SIDS or Sudden Infant Death Syndrome.
In 1975 the Tinnings' 5-month-old son was determined to have died of pulmonary edema. In 1978, their 3-month-old girl's death was attributed to SIDS. The 1980 death of a 3-month old son was undetermined, and and in 1981 a boy the couple was in the process of adopting died of what was supposedly bronchial pneumonia.
All of the deaths had been attributed to "bad genes" until the adopted child passed away.
Over the years authorities had grown suspicious but no charges were brought until the 1985 death of 4-month-old Tammy-Lynn, the couple's fourth child. While Tinning was indicted on charges related to the deaths of three of her children, she was only convicted of Tamy-Lynn's. and was sentenced to 20 years to life.
Initially Tinning denied killing any of her children but during her second parole hearing in 2011 she confessed that, "After the deaths of my other children ... I just lost it. (I) became a damaged worthless piece of person and when my daughter was young, in my state of mind at that time, I just believed that she was going to die also. So I just did it."
Joseph Tinning has stood by his wife throughout her incarceration despite the fact that in 1974 he was hospitalised after she put barbiturates into his grape juice. He did not press charges and has visited his wife in the Taconic Correctional Facility in Bedford Hills monthly. He is not a suspect in any of the deaths.
Upon hearing of his wife's parole — the decision to release her came from prison at her 7th appearance before the parole board — Joseph told the Daily Gazette "it's very emotional. She was very emotional telling me."
In 2013, Tinning told the parole board that if she were released she would, "(work) in the church and the community where my help is needed, such as volunteering at a food bank and homeless shelters."
While there are no reliable statistics on just how many people suffer from FDIA because many cases go undetected, experts "suggest that about 1,000 of the 2.5 million cases of child abuse reported annually are related to FDIA." Generally the disorder is more common in women than in men.
While Tinning will remain under parole supervision for the rest of her life, authorities believe she is not expected to reoffend. Dr. Michael Baden who worked with prosecutors on the case told People:“She’s not going to kill again. She only kills the babies she has.”