The body of Sister Maria Laura Mainetti was discovered in Marmitte dei Giganti park in Chiavenna on the morning of7 June 2000. Mainetti, a 60-year-old Catholic sister and Sister of the Cross who was mother superior of a local convent which specialised in helping juvenile delinquents, had left the convent the night before to meet with a girl who had telephoned her. Mainetti had been stabbed 19 times. Three weeks later, police arrested three girls aged 16 and 17 on suspicion of the murder. The three girls, Ambra Gianasso, Milena De Giambattista and Veronica Pietrobelli, had no prior history of crime or violence and came from middle-class families. After a witness told police that he had seen the four together on 6 June, the girls' telephones were monitored by police, and in one phone call, two of the girls discussed the killing. A clump of hair belonging to one of the girls was found in Mainetti's clenched hand. In custody, the girls initially said they killed the sister "for a game", later saying they killed her in a satanic sacrifice. Initially, the girls had wanted to kill the parish priest, but decided that Mainetti, who had previously taught them catechism, would be an easier target. One of the girls telephoned Mainetti claiming to have been raped and impregnated and to be considering an abortion, and they arranged to meet in Marmitte dei Giganti park at 22:00 on 6 June. After walking with Mainetti to the park, the girls made the sister kneel on the ground and shouted abuse at her. De Giambattista beat Mainetti with a brick and Gianasso repeatedly rammed the sister's head against a wall. The three girls then took turns in stabbing Mainetti with a kitchen knife. The girls' intention was to stab the sister 18 times—6 times per girl, as per the number of the beast—but they instead stabbed her 19 times, "ruining" the ritual. As she was being attacked, Mainetti prayed, asking God to forgive the girls.
Legal proceedings
De Giambattista, Gianasso and Pietrobelli were summarily tried at the juvenile court of Milan on 9 August 2001, with the prosecution requesting sentences of 15 years and 4 months for Gianasso, 11 years and 4 months for Pietrobelli, and 10 years and 4 months for De Giambattista. The latter two were convicted of murder and sentenced to 8 years and 6 months' imprisonment, the court taking into account that they were partially insane at the time of the crime. Gianasso was found not guilty of murder by reason of insanity and was ordered to spend a minimum of three years at a youth detention centre. The prosecution appealed for Gianasso's acquittal to be overturned to a conviction with a sentence of 12 years, 7 months and 10 days' imprisonment, and for De Giambattista and Pietrobelli's sentences to be upheld. On 4 April 2002, the appeal court of Milan overturned Gianasso's acquittal and declared her only partially insane at the time of the crime, sentencing her to 12 years and 4 months' imprisonment, while upholding De Giambattista and Pietrobelli's sentences. Gianasso appealed her sentence, and on 17 January 2003, she was released from prison as the Supreme Court of Cassation had not reached a verdict on the appeal. She returned to prison six days later after the court upheld her sentence. Pietrobelli was released from prison on 4 July 2004. Following her release, she participated in a community service program in Rome for two years. De Giambattista was released on 2 May 2006 and also participated in a community service program. From December 2007 until her release, Gianasso was also allowed out of prison during daytime hours to do community service.
Aftermath
, Bishop of the Diocese of Como, opened the diocesan phase of Mainetti's beatification process at the Collegiate Church of Saint Lawrence in Chiavenna on 23 October 2005. On 20 March 2008, he announced that the request for the initiation of her beatification process had been approved. The Congregation for the Causes of Saints declared her a martyr, eliminating the need for recognition of a miracle. The Congregation declared her a martyr again on 19 June 2020. Her beatification is scheduled for 6 June 2021, the twenty-first anniversary of her murder. On 26 February 2019, Mainetti's remains were exhumed from Chiavenna cemetery and placed in the Collegiate Church of Saint Lawrence.
