Björn Pétursson farmed at Öxl, in Breiðavík on the Snæfellsnes peninsula in western Iceland, and was executed in 1596. History knows him as Axlar-Björn, which means Björn of Öxl. He is the best known killer in Icelandic history, and almost everything told about him is later than his life. The documents from his own time are two rulings of the Althing, Iceland's national assembly, made in 1596 and 1597. Neither describes a single victim. They say that he had confessed to murders the assembly called unheard of, that he had already been executed, and that his wife was to be examined and, on the 1597 ruling, not punished without new proof.
Everything else, the numbers, the stories and the details of the farm, comes from annals written decades afterward and from folktales written down in the nineteenth century, and the legend departs from the Althing record in several places.
He appears under several forms in the sources. Björn Pétursson is the name in the Althing book. Axlar-Björn is the name by which later tradition knows him, formed from the farm of Öxl, whose genitive form is Axlar. He is also called Björn í Öxl, Björn at Öxl. The heading over the 1596 ruling in the Althing book calls him Manndrápa-Björn, a name that means Björn of the killings. In plain Latin letters his name is Bjorn Petursson.
Öxl lay in Breiðavík, also written Breiðuvík, near Búðir on the south side of the Snæfellsnes peninsula. Tradition puts his birth around 1555; his childhood and his family before his marriage are not on record. His wife was Þórdís Ólafsdóttir (plain Latin: Thordis Olafsdottir), the name given in the Althing book.
The assembly that dealt with him was the Laugarbrekka assembly, a local assembly. Laugarbrekka was the assembly site nearest to Öxl, and the historian Már Jónsson, writing for the University of Iceland, considers the tradition that places the sentence there probably reliable. Björn was sentenced to death at Laugarbrekka and executed in 1596. The Icelandic scholar Gísli Sigurðsson gives the same year. One annalist, Pétur Einarsson of Ballará, was unsure whether the matter belonged to 1596 or 1597, but the Althing ruling of 1596 already speaks of Björn as executed.
Nothing in the contemporary record describes the hearing itself: who testified, what he said, when he confessed or how the inquiry began are all missing. The wording of the Althing ruling is the only direct evidence that a confession was made.
The ruling of 1596 is printed in the Althing books (Alþingisbækur III, page 64). It records that a man named Kastian Boch asked the Althing for a judgment and advice concerning Þórdís Ólafsdóttir, who had been married to Björn Pétursson, "because of the unheard-of murders that the same Björn had confessed". The assembly thought it best that Kastian name twelve sensible and trustworthy people. Már Jónsson explains the procedure: Þórdís was under suspicion and had to clear herself by an oath of twelve, six men and six women, who would swear whether she was guilty or innocent. The sheriff, the sýslumaður, was to bring the case to court. She was to be held in custody until it was settled. The matter was not finished that winter.
The words "unheard-of murders" matter for another reason. Már Jónsson reads the plural and the wording as showing that there were more than three or four killings. In his words, it should be clear from the phrasing that the murders were more than three or four, and what people believed was that they were many. He adds that the numbers may not be trustworthy. He does not say whether the killings fell in separate events or in one run; the ruling itself gives neither dates nor places nor names of the dead.
The second document is in the Althing book at page 101. The Althing ruled that the king's agent in the Snæfellsnes district should look into the matter further. If nothing new came to light, the ruling says, "then we do not know how to sentence her to punishment". The sheriff was to continue the inquiry before the next travelling court. The ruling does not record a verdict of guilty against her, and Már Jónsson reads the two rulings together as pointing to her innocence. The outcome of the further inquiry is not on record.
The first written account of the number of killings comes from Björn Jónsson of Skarðsá, born in 1574 and a member of the law council from 1616. His annal, compiled in the 1630s, says that Björn Pétursson had killed nine men, whom he confessed to himself. This is the lowest of the annal figures and the one closest to his time, and it is a later claim, written about forty years after the execution.
Skarðsárannáll also says that his wife took part and that she was not executed because she was pregnant. Már Jónsson judges that the annalist was wrong about Þórdís, because the Althing rulings show her case still open in 1596 and 1597 and point to her innocence.
Pétur Einarsson of Ballará, born in 1597 and a member of the law council from 1627, wrote after 1640 and gives the number as fourteen or fifteen. A third annal, by Oddur Eiríksson at Fitjar in the later seventeenth century, builds on Skarðsárannáll and gives eighteen or fourteen. Gísli Þorkelsson's annal from Setberg, about 1710, also follows Skarðsárannáll but adds stories of the folk-tale kind. Skarðsárannáll was printed at Hrappsey in 1774 with a note that the dead numbered fourteen or eighteen. In 1826 Jón Espólín's Íslands árbækur repeated fourteen or eighteen and added an episode that Már Jónsson calls invented.
None of these figures rests on a list of names. Each is a later claim, and Már Jónsson treats all of them with caution.
Þórdís Ólafsdóttir is the one other person in the record. The 1596 ruling shows her suspected and held while a jury of twelve was arranged. The 1597 ruling declines to punish her without further proof. The record contains no conviction of her.
The popular retellings disagree with this. In the folktale she is named Steinunn, is described as a servant girl who married Björn and is said to have been put to death after giving birth. Other popular articles name her Þórdís and say that both were sentenced to death, or contradict themselves on her fate. These are tellings of the legend; the Althing book does not support them.
Tradition gives Björn a son, Sveinn, called skotti. The Vísindavefur answer by Gísli Sigurðsson says that Sveinn was executed in 1648 for a later crime of his own. His parentage rests on tradition; the Althing rulings do not mention a son.
The best known telling was sent to Jón Árnason in 1860 by the Reverend Sveinn Níelsson, who took it down from an old and perceptive local man, and was printed in 1864 in Jón Árnason's collection of Icelandic folktales. Páll Melsteð published an earlier version in the newspaper Íslendingur in 1860, and Gísli Konráðsson wrote another that Jón Árnason did not use. Þorsteinn frá Hamri, in a 1961 article, called Gísli's version the most complete.
In the tale, Björn killed travellers who passed his farm, eighteen people in all, until a survivor exposed him. His nature is said to have been evil before he was born. All of this is folklore. Neither Althing ruling mentions travellers, a survivor or the number eighteen.
The story has had a long afterlife. Úlfar Þormóðsson wrote a historical novel on it, Þrjár sólir svartar (1988), and Megas used Björn and Sveinn as characters in his 1994 work Björn og Sveinn. A student thesis on Axlar-Björn in the sources and folktales was written by Ebba Guðný Guðmundsdóttir in 1999.
The number of victims is the central uncertainty. The contemporary record says "murders" without a figure, and a historian reads it as more than three or four. Nine, fourteen or fifteen, and fourteen or eighteen are annal figures written decades later; eighteen is the folktale figure. No victim is named in any of them.
The year of the execution is given as 1596. One annalist hesitates between 1596 and 1597, but the Althing ruling of 1596 already treats him as executed.
The wife's outcome differs by source. Skarðsárannáll says she was spared because she was pregnant; the Althing book shows her under suspicion in 1596 and, in 1597, not to be punished without new evidence; folk tellings say she was put to death.
His birth around 1555 is tradition. The son and his death in 1648 are given in tradition and by a scholarly answer, and neither the son nor the year appears in the Althing rulings.
Whether the killings fell in separate events cannot be settled from the record: it speaks of several murders and gives no dates or places for any.
About 1555: tradition places Björn Pétursson's birth.
Before 1596: the murders he confessed to; dates and places are not on record.
1596: sentenced at the Laugarbrekka assembly and executed; the Althing of that year hears Kastian Boch's request about Þórdís Ólafsdóttir and orders a jury of twelve.
1597: the Althing rules that the king's agent in Snæfellsnes shall inquire further and that she is not to be punished without new proof.
1630s: Björn Jónsson of Skarðsá compiles his annal, which gives nine confessed murders.
After 1640: Pétur Einarsson of Ballará writes the figure fourteen or fifteen.
1648: Sveinn skotti is executed, according to tradition.
About 1710: Setbergsannáll adds folk-tale stories.
1774: Skarðsárannáll is printed at Hrappsey.
1826: Jón Espólín's Íslands árbækur repeats fourteen or eighteen.
1860 to 1864: Páll Melsteð's and Sveinn Níelsson's tellings; the second is printed in Jón Árnason's collection.
1988: Úlfar Þormóðsson's novel Þrjár sólir svartar.
1994: Megas, Björn og Sveinn.
2025: the University of Iceland's Vísindavefur publishes Már Jónsson's answer on the number of victims.