Margit Julianna Elek, known later as Margit Filó, was born on June 10, 1914, on Attila Street in Makó, Hungary. She grew up in a poor family and had to work from a young age to help support them. By 1938, she faced serious health issues and was admitted to a closed psychiatric hospital due to schizophrenia. After her release, she found a job at Ferenc nagy's poultry farm in Makó.

In 1949, Margit started to have problems with her employer regarding the work conditions. She decided to take legal action and successfully sued him for 14,000 forints. With this money, she purchased a housing complex located on 38 Hétvezér Street in the Rókus District of Szeged. Margit was unhappy that she had to live on the ground floor while the poorer tenants were given the upper floor apartments by the city.

During her early adult life, Margit mostly had friendships with women. However, in 1950, she married Mihály Barna, a chimney sweeper and former soldier. In 1952, she was again hospitalized for a short time. After her discharge, she and her husband bought a house in Debrecen. Despite having more financial stability, Margit often wore dirty clothes while doing household chores.

Margit and Mihály lived together for eight years. Over time, his health began to decline. His mother moved in with them to help care for him. In the late 1950s, both Mihály and his mother passed away in quick succession. There was speculation around their deaths, but it could not be proven that they were murdered.

In the year following her husband's death, Margit Julianna Elek, known as Filó, started a relationship with a wealthy farmer named Sándor Varga. They settled in Kiszombor, bringing along a helper named Lajosné Biczó. In October 1958, Filó incapacitated Biczó with dissolved medication in water and suffocated her while she was unconscious. An autopsy revealed homicide, but the authorities could not conclusively prove her guilt, so she was released. Filó inherited Biczó's belongings, according to her will.

In autumn 1959, Filó married Varga, who made her his sole heir. Shortly after their wedding, on Christmas Day, she poisoned cabbage that she prepared for him using poison extracted from thorn apple leaves. Varga and two family members got very ill but survived. Filó tried again two days later by poisoning a soup, which led to Varga's death. She sold his property after he died and moved back to Rókus.

In 1963, Filó targeted her sick neighbor, 75-year-old Iloná Siegel. After making a financial agreement with Siegel, Filó ordered a tombstone. Two weeks later, she poisoned her and strangled her while Siigel was unconscious. The coroner did not find anything suspicious, allowing her to inherit Siegel's 20,000 forint estate.

As time went on, Filó wanted to replace her poor tenants with industrial workers. By 1968, she had convinced several residents to leave but faced resistance from 77-year-old widow Mihály Tóthpál. On July 9, 1968, Filó killed Tóthpál by poisoning and strangling her. During the attack, Filó broke several of Tóthpál's ribs, which were discovered by coroners. This led to Filó being arrested.

While searching her home, authorities found human skulls and toxic substances. Filó claimed she had stolen the skulls and used the poisons for love potions. Investigators exhumed the bodies of her previous victims and confirmed they had been poisoned, except for one. They also discovered that a will from Biczó had been forged.

In court, Filó argued that she killed her victims to relieve their suffering and benefit the state by reducing pension payments. Given her history of mental health issues, the court ordered a psychiatric evaluation. Filó initially denied responsibility but later made odd claims about having nine husbands. She was diagnosed with schizophrenia and dissociative identity disorder, deemed unfit to stand trial, and transferred to Lipótmező Mental Asylum, where she remained until her death in 1979.