María de las Mercedes Bernardina Bolla Aponte de Murano was born on May 20, 1930, in Corrientes, Argentina. Not much is known about her childhood or family background. She grew up in a time when Argentina was facing various social and economic challenges. The details of her early education and life in her youth are not well documented.

As she matured, she lived in Buenos Aires, where she became known by the nickname Yiya Murano. She had a reputation in her community, but again, specific details about her relationships and personal life during her early adulthood are sparse. The lack of clear records makes it difficult to paint a full picture of her early years.

Yiya Murano's life took a significant turn in the late 1970s when she became involved in serious legal issues. Before this period, her life was relatively quiet, and she engaged with people in her neighborhood. However, her later actions overshadowed her earlier life.

She lived in a neighborhood where she was known to borrow money from acquaintances. Some reports indicate that she had a complex relationship with her neighbors, which later became crucial in the events that unfolded in her life. The absence of thorough records from her early life contributes to the enigma surrounding her background.

On February 10, 1979, Nilda Gamba, a neighbor of María de las Mercedes Bernardina Bolla Aponte de Murano, died suddenly. Just a few days later, on February 19, Murano's friend, Leila Chicha Formisano de Ayala, also died in a similar manner. Both women had reportedly been owed money by Murano. Upon investigation, both bodies showed signs of cyanide poisoning.

On March 24, 1979, Murano's cousin, Carmen Zulema del Giorgio de Venturini, died after falling down the stairs of her apartment building. Initially, her death was attributed to cardiac arrest. However, it was later discovered that a promissory note worth 20 million Argentine peso ley was missing from her belongings. Eyewitnesses, including the building's doorman, reported that Murano had visited Zulema on the day of her death. Murano had asked for a copy of Zulema's apartment keys, claiming she needed to warn her relatives. After entering the apartment, Murano left quickly, taking papers and a jar with her. She was heard complaining about the deaths of her friends. An autopsy revealed cyanide in Zulema's system, and investigators found the same poison in the jar and in some petit fours that Murano had brought.

Murano was arrested on April 27, 1979, at her home on Mexico Street. In 1980, she was found unconscious in prison and later had one of her lungs removed during surgery. In 1985, she was convicted of the murders. Despite the evidence, Murano maintained her innocence, famously stating, "I never invited anyone to eat."

After serving 16 years in prison, Murano was released. She showed her gratitude to the judges who released her by sending them a box of chocolates.