A woman who testified against her own father after her mother was murdered in a notorious mafia killing in Italy is believed to have taken her own life. Denise Cosco was found critically injured on Sunday and died later in hospital in Rome.

Her mother Lea Garofalo, who was killed in 2009, became a powerful symbol of resistance to the mafia after turning witness for the state against the ' Ndrangheta clan in southern Italy. Those close to Cosco recall her bravery in speaking out at her father's trial, but also her tremendous struggle in the years that followed.

At 35, she died at the same age her mother was when she was murdered. Enza Rando, a senator and anti-mafia lawyer who represented Cosco at the murder trial, described her death as "a profound wound for the entire country", and proof that the mafia not only kills, but creates "true monsters in the lives and souls" of those who survive.

Francesca Rispoli, co-president of the anti-mafia organisation Libera, said the death highlighted the struggle experienced by many who break with organised crime." The mafia, it's not just something physical.

You can leave. You can change your name," she told the BBC.

" But there is still a tie, a family tie, that stays… deep inside and is impossible to overcome." Cosco, like her mother, had lived under state protection with a new name and identity for many years.

Friends say she struggled with mental health problems and addiction." Maybe this is a sign that those trying to lead another life need more support.

Not just for one year – maybe their whole life," Rispoli argued, as organised crime groups in Italy – especially the ' Ndrangheta - involve close-knit family networks. In Cosco's case, both her mother's family and her father were tied to the mafia.

She had always refused to believe her father's story that her mother had abandoned her to start a new life in Australia. In fact, he had tricked Garofalo to a meeting, then had her strangled, her body dismembered then incinerated.

Several years later, a statement by one of the killers finally allowed police to rec over some fragments of bone and a necklace, which Cosco identified. Her father and three accomplices were already serving life in prison.

At the trial, Cosco described herself as a "proud witness for justice" and said she had taken the difficult choice to testify – speaking from behind a screen – because she wanted "inner freedom to start over" with her life. Prosecutors have now opened an investigation to determine whether there was any incitement to suicide and her phone has been seized for analysis.