Elizabeth was engaged at age 15 to Ferenc Nádasdy, the son of Baron Tamás Nádasdy de Nádasd et Fogarasföld and his wife, Orsolya Kanizsay  in what was likely a political arrangement within the circles of the aristocracy. The couple married on 8 May 1575 at the palace of Varannó. Approximately 4,500 guests attended the wedding. Elizabeth moved to Nádasdy Castle in Sárvár and spent much time on her own, while her husband studied in Vienna.  Nádasdy’s wedding gift to Báthory was his home, Csejte Castle. The castle had been bought by his mother in 1579 and given to Ferenc, who transferred it to Elizabeth during their nuptials situated in the Little Carpathians near Trencsén (now Trenčín), together with the Csejte country house and 17 adjacent villages.[citation needed] The castle itself was surrounded by a village and agricultural lands, bordered by outcrops of the Little Carpathians.

In 1578, Nádasdy became the chief commander of Hungarian troops, leading them to war against the Ottomans. With her husband away at war, Elizabeth Báthory managed business affairs and the estates. That role usually included responsibility for the Hungarian and Slovak people, providing even medical care.  During the length of the Long War (1593–1606), Elizabeth was charged with the defense of her husband’s estates, which lay on the route to Vienna. The threat was significant, for the village of Csejte had previously been plundered by the Ottomans while Sárvár, located near the border that divided Royal Hungary and Ottoman-occupied Hungary, was in even greater danger. She was an educated woman who could read and write in four languages. There were several instances where she intervened on behalf of destitute women, including a woman whose husband was captured by the Turks and a woman whose daughter was raped and impregnated.

Around 1585, Elizabeth gave birth to a daughter, Anna (later the wife of Miklós Zrinyi VI, who died after 1605). More children followed: daughter Katalin, son György, daughter Orsolya (later wife of István II Benyó), and sons Pál (1593/1597-1633/1650 – father of Ferenc Nádasdy II), András (1598–1603), and Miklós (husband to Zsuzsanna Zrinyi). All of her children were cared for by governesses, as Elizabeth had been.  Elizabeth’s husband Ferencz died on 4 January 1604 at the age of 48, reportedly due to an unknown illness or battle wound. The couple had been married for 29 years. Before dying, Ferenc Nádasdy entrusted his heirs and widow to György Thurzó, who would eventually lead the investigation into Elizabeth’s crimes.

Between 1602 and 1604, after rumors of Báthory’s atrocities had spread through the kingdom, Lutheran minister István Magyari made complaints against her, both publicly and at the court in Vienna. The Hungarian authorities took some time to respond to Magyari’s complaints. Finally, in 1610, King Matthias II assigned György Thurzó, the Palatine of Hungary, to investigate. Thurzó ordered two notaries to collect evidence in March 1610. In 1610 and 1611, the notaries collected testimony from more than 300 witnesses. The trial records include the testimony of the four defendants, as well as thirteen witnesses. Priests, noblemen and commoners were questioned. Witnesses included the castellan and other personnel of Sárvár castle.

According to all testimony, Báthory’s initial victims were the adolescent daughters of local peasants, many of whom were lured to Csejte by offers of well-paid work as maidservants in the castle. Later, she is said to have begun to kill daughters of the lesser gentry, who were sent to her gynaeceum by their parents to learn courtly etiquette. Abductions were said to have occurred as well. The atrocities described most consistently included severe beatings, burning or mutilation of hands, biting the flesh off the faces, arms and other body parts, freezing or starving to death. The use of needles was also mentioned by the collaborators in court.

Some witnesses named relatives who died while at the gynaeceum. Others reported having seen traces of torture on dead bodies, some of which were buried in graveyards, and others in unmarked locations. However, two witnesses (court officials Benedikt Deseo and Jakob Szilvassy) actually saw the Countess herself torture and kill young servant girls. According to the testimony of the defendants, Elizabeth Báthory tortured and killed her victims not only at Csejte but also on her properties in Sárvár, Németkeresztúr, Bratislava (then Pozsony, Pressburg), and Vienna, and elsewhere. In addition to the defendants, several people were named for supplying Elizabeth Báthory with young women, procured either by deception or by force. A little-known figure named Anna Darvulia was rumored to have influenced Báthory, but Darvulia was dead long before the trial.

Thurzó went to Csejte Castle on 30 December 1610 and arrested Báthory and foemtész, Ilona Jó, Katarína Benická, and János Újváry (“Ibis” or Fickó). Thurzó’s men reportedly found one girl dead and one dying and reported that another woman was found wounded while others were locked up. The countess was put under house arrest.  Thurzó debated further proceedings with Elizabeth’s son Paul and two of her sons-in-law. A trial and execution would have caused a public scandal and disgraced a noble and influential family (which at the time ruled Transylvania), and Elizabeth’s considerable property would have been seized by the crown. Thurzó, along with Paul and her two sons-in-law, originally planned for Elizabeth to be spirited away to a nunnery, but as accounts of her murder of the daughters of lesser nobility spread, it was agreed that Elizabeth Báthory should be kept under strict house arrest, but that further punishment should be avoided.  King Matthias urged Thurzó to bring Elizabeth to trial and suggested she be sentenced to death, but Thurzó successfully convinced the king that such an act would negatively affect the nobility. Thurzó’s motivation for such an intervention is debated by scholars. It was determined that Matthias would not have to repay his large debt to Elizabeth.

The trial of Báthory’s accomplices began on 2 January 1611 at Bicse, presided over by Royal Supreme Court judge Theodosious Syrmiensis de Szulo and 20 associate judges. Dozens of witnesses and survivors, sometimes up to 35 a day, testified. All but one of the Countess’s servants testified against her–the one who refused had her eyes gouged out and her breasts removed before being burned at the stake. In addition to the testimony, the court also examined the skeletons and cadaver parts found as evidence.

The exact number of Elizabeth Báthory’s victims is unknown, and even contemporary estimates differed greatly. During the trial, Szentes and Ficko reported 36 and 37 victims respectively, during their periods of service. The other defendants estimated a number of 50 or higher. Many Sárvár castle personnel estimated the number of bodies removed from the castle at between 100 to 200. One witness who spoke at the trial[who?] mentioned a book in which Báthory supposedly kept a list of a total of over 650 victims, and this number has passed into legend. In a second part of the trial, a newly discovered register was entered as evidence that suggested there could have been as many as 650 victims, but this could not be proven, and the count remained at 80. Reportedly, the location of the diaries is unknown but 32 letters written by Báthory are stored in the Hungarian state archives in Budapest.

Three of the defendants – Semtész, Jó and Ficko – were condemned to death and their sentences carried out immediately. Before being burned at the stake, Semtész and Jó had their fingers ripped off their hands with hot pincers. Ficko, who was deemed less culpable, was beheaded, and his body burned. Benická was sentenced to life imprisonment, since testimony indicated that she was dominated and bullied by the other women.  Following the trial, a red gallows was erected near the castle to show the public that justice had been done.

Báthory was imprisoned in Čachtice Castle. She was kept bricked in a set of rooms, with only small slits left open for ventilation and the passing of food. She remained there for four years, until her death. On 24 August 1614, a guard looked through one of the slots and observed Elizabeth Báthory lying dead face-down on the floor. Since there were several plates of food untouched, her actual date of death is unknown. She was buried in the church of Csejte, but due to the villagers’ uproar over having “The Tigress of Csejte” buried in their cemetery, her body was moved to her birth home at Ecsed, where it is interred at the Báthory family crypt.