From Tracy Marks:
Little is known about the circumstances under which Agostino Tassi was charged for raping Artemisia Gentileschi, but scholars believe that her father heard rumors and confronted them both. Both Cosimo Quorli (who had tried but failed to rape Artemisia, who had stolen one of her paintings, and who had helped Agostino plan visits to her house when her father was absent) were charged. The trial lasted for seven months in 1612, and received considerable publicity.
The transcripts of the trial, included in Mary Garrard’s Artemisia Gentileschi, reveal that:
a) Tuzia, supposedly an older friend of Artemisia who lived in the same house as the Gentileschi’s, betrayed Artemisia by letting Agostino in to Artemisia’s house through her apartment.
b) Agostino was a convicted rapist, who had previously served time in jail, and had been known to have raped both his sister-in-law and his previous wife. His wife was missing, presumed dead, and everyone believed that he had hired bandits to kill her. Artemisia did not know that he was married until the middle of the trial.
c) Agostino was obsessed with Artemisia, had prevented her from marrying Modenese, whom her father had arranged for her to marry, had spied on her and hired men to watch her around the clock, and had been known to have many jealous rages in regard to her proximity to other men. He also had bragged to many that he had deflowered her.
d) Since the first sexual encounter, Agostino had been continually promising Artemisia that he would marry her, and continually postponing the marriage, but using his promise as a means of convincing her to continue sexual relations with him.
During the trial, Artemisia was tortured with the sibille, thumbscrews, involving cords of rope tied around her hands and pulled tightly, in order to “prove” that she was telling the truth. During the torture, which of course seriously injured her hands, she was repeatedly asked whether or not Tassi had raped her, and she continually responded, “it is true, it is true.”
Read more about Gentileschi here