Ferdinand IV died on 7 September 1312 in the city of Jaén, without anyone seeing him die.
History and legend have intertwined indissolubly in what concerns the death of the monarch, who received at his death the nickname of "the Summoned", because of the mysterious circumstances in which it occurred.
Ferdinand IV died aged 26, and when he died he left an only 1-year-old son, who would reign as Alfonso XI of Castile.

The Chronicle of Fernando IV, written around 1340, almost thirty years after the death of the king, describes the death of the Castilian-Leonese monarch in Chapter XVIII of the work, and the Carvajal brothers, thirty days Before that of Ferdinand IV, although it does not specify how the latter died:
The King left Jaén, and went to Martos, and being and ordered to kill two knights who were in his house, because they were blamed for the death of a knight who was say they killed when the King was in Palencia, after leaving the house of the King one night, namedh Juan Alonso de Benavides.
It is these knights, when the King ordered them to be killed, seeing that they were killed with treason, they said that they would summoned the King that he would appear before God with them on a trial after thirty days from that moment.
They were dead, and the next day was the King with his army in Alcaudete, and every day he waited for the infante John of Castile, according to what was expectred from him...It is the King being in this siege of Alcaudete, took a very great ailment in such a way that he came to Jaén with the disease, and ate meat every day, and drank wine...And the day Thursday, seven days of September, the eve of Sancta Maria, the King went to bed, and a little after half a day they found him dead in hs bed, so that no one saw him die.
This Thursday, the thirty days of the summons of the knights that he had killed in Martos were fulfilled...
In the chapter III of the Chronicle of Alfonso XI, the death of Ferdinand IV is described in the same way as described in the Chronicle of Ferdinand IV.
The historian Diego Rodríguez de Almela, in his work Valerio de las historias escolásticas y de los hechos de España, which was written around the year 1472, related as follows the death of the monarch:
King Ferdinand IV of Castile, who took Gibraltar, was in Martos, and were acussed before him two knights, called the one Pedro Carbajal and the other Juan Alfonso de Carbajal, his brother, who both belonged to his court, that a night, while the King was in Palencia, they killed a knight named Gómez de Benavides, loved very much by the King, giving many indications and presumptions because it seemed that they had been killed him.
King Ferdinand , using rigorous justice, made the two brothers arrest, and thrown from top of the Rock of Martos; before they were thrown out they said that God was their witness and knew the truth that they were not guilty in that death, and that the King ordered them to be kill without reason, that he was summoned from that day that they died in thirty days that he should appear with them in judgment before God.
The knights were killed, and King Ferdinand came to Jaén.
He realized that two days before the time was over he felt angry, ate meat and drank wine.
As the day of the thirty-day period that the knights he killed placed him, he wanted to leave for Alcaudete, that his brother the infante Peter had taken the Moors, ate early, and lay down to sleep, which was in summer; and when they came to awaken him, they found him dead in bed, that no one should see him die.
A great deal must be paid to the Judges before they proceed to execute justice, especially of blood, until they truly know the fact that justice must be carried out.
As in the Genesis it reads: whoever draws blood without sin, God will demand it.
This King did not have the way that suited the execution of justice, and therefore ended as it.

Martín Ximena Jurado, a historian and chronicler of the 17th century in his work Catálogo de los Obispos de las Iglesias Catedrales de Jaén y Anales eclesiásticos de este Obispado, described the Roya
Ferdinand IV died on 7 September 1312 in the city of Jaén, without anyone seeing him die. History and legend have intertwined indissolubly in what concerns the death of the monarch, who received at his death the nickname of "the Summoned", because of the mysterious circumstances in which it occurred. Ferdinand IV died aged 26, and when he died he left an only 1-year-old son, who would reign as Alfonso XI of Castile.
The Chronicle of Fernando IV, written around 1340, almost thirty years after the death of the king, describes the death of the Castilian-Leonese monarch in Chapter XVIII of the work, and the Carvajal brothers, thirty days Before that of Ferdinand IV, although it does not specify how the latter died:
The King left Jaén, and went to Martos, and being and ordered to kill two knights who were in his house, because they were blamed for the death of a knight who was say they killed when the King was in Palencia, after leaving the house of the King one night, namedh Juan Alonso de Benavides. It is these knights, when the King ordered them to be killed, seeing that they were killed with treason, they said that they would summoned the King that he would appear before God with them on a trial after thirty days from that moment. They were dead, and the next day was the King with his army in Alcaudete, and every day he waited for the infante John of Castile, according to what was expectred from him...It is the King being in this siege of Alcaudete, took a very great ailment in such a way that he came to Jaén with the disease, and ate meat every day, and drank wine...And the day Thursday, seven days of September, the eve of Sancta Maria, the King went to bed, and a little after half a day they found him dead in hs bed, so that no one saw him die. This Thursday, the thirty days of the summons of the knights that he had killed in Martos were fulfilled...
In the chapter III of the Chronicle of Alfonso XI, the death of Ferdinand IV is described in the same way as described in the Chronicle of Ferdinand IV. The historian Diego Rodríguez de Almela, in his work Valerio de las historias escolásticas y de los hechos de España, which was written around the year 1472, related as follows the death of the monarch:
King Ferdinand IV of Castile, who took Gibraltar, was in Martos, and were acussed before him two knights, called the one Pedro Carbajal and the other Juan Alfonso de Carbajal, his brother, who both belonged to his court, that a night, while the King was in Palencia, they killed a knight named Gómez de Benavides, loved very much by the King, giving many indications and presumptions because it seemed that they had been killed him. King Ferdinand , using rigorous justice, made the two brothers arrest, and thrown from top of the Rock of Martos; before they were thrown out they said that God was their witness and knew the truth that they were not guilty in that death, and that the King ordered them to be kill without reason, that he was summoned from that day that they died in thirty days that he should appear with them in judgment before God. The knights were killed, and King Ferdinand came to Jaén. He realized that two days before the time was over he felt angry, ate meat and drank wine. As the day of the thirty-day period that the knights he killed placed him, he wanted to leave for Alcaudete, that his brother the infante Peter had taken the Moors, ate early, and lay down to sleep, which was in summer; and when they came to awaken him, they found him dead in bed, that no one should see him die. A great deal must be paid to the Judges before they proceed to execute justice, especially of blood, until they truly know the fact that justice must be carried out. As in the Genesis it reads: whoever draws blood without sin, God will demand it. This King did not have the way that suited the execution of justice, and therefore ended as it.
Martín Ximena Jurado, a historian and chronicler of the 17th century in his work Catálogo de los Obispos de las Iglesias Catedrales de Jaén y Anales eclesiásticos de este Obispado, described the Roya
Ferdinand IV of Castile