The year 1852 was difficult for Mérimée. On 30 April 1852, his mother, who lived with him and was very close to him, died. He also became entangled in a legal affair involving one of his friends, a professor of mathematics from Pisa named Count Libri Carrucci Della Sommai, who settled in France in 1824 and became a professor at the Sorbonne, a member of College of France, a holder of the Legion of Honor, and the Inspector General of Libraries of France. It was discovered that under his academic cover he was stealing valuable manuscripts from state libraries, including texts by Dante and Leonardo da Vinci, and reselling them. When he was exposed, he fled to England, taking 30,000 works in sixteen trunks, and claimed that he was victim of a plot. Though all the evidence was against Count Libri, Mérimée took his side, and in April 1852 wrote a scathing attack on Libri's accusers in the "Revue des deux Mondes". He attacked the incompetence of the prosecutors and blamed the Catholic Church for inventing the case. On the same day that his mother died, he was summoned before the state prosecutors, and was sentenced to fifteen days in prison and fined one thousand francs. The "Revue des deux Mondes" was also fined two hundred francs. Mérimée offered his resignation from the government, which was refused. He served his sentence inside one of his listed historic monuments, the Palais de la Cité prison, passing the time studying Russian irregular verbs.