"This was the most shocking murder I have ever looked into," said one veteran Shin Bet investigator after a five-week inquiry into the murder of the Fogel family in Itamar.
Two suspects whose culpability, the authorities argue, is in little doubt after DNA traces linked them to the scene of the attack, now await a military trial.
"They both reconstructed the murders in a cold-blooded way," said the investigator. "At no point did they express any remorse."
Even in a country that has suffered generations of war and terror attacks, the stabbings of Ruth and Rabbi Ehud Fogel, along with their sons Yoav, 11, Elad, 4, and their three month-old baby Hadas, shocked an entire nation.
The alarm was raised only an hour and a half after the murders, in the early hours of March 12, a Shabbat night.
After securing the village, the IDF forces began hunting the killers at around four in the morning, and identified clear tracks leading to the adjacent Palestinian village of Awarta.
Awarta has 8,000 inhabitants. Suspicion fell at first on the local Kawarik clan, two of whose male members had been killed a year earlier in an incident involving the IDF. It was thought that the motive was revenge for those deaths and dozens of men from the Kawarik family were arrested and questioned.
But that line of inquiry proved fruitless. None of the suspects turned out to have any connection to the murders.
The investigation, carried out jointly by the IDF and Shin Bet, intensified as DNA samples were taken from men and women in Awarta, in an attempt to match forensic evidence from the Fogel house with a specific family in the village.
Finally, on April 5, over three weeks after the murder, in an operation carried out by the elite Duvdevan unit, 17-year-old Hakim Awad was arrested at his home in Awarta and, under Shin Bet questioning, admitted to having participated in the murders. He gave away the name of his partner, 18-year-old Amjad Awad - no relation - who was arrested five days later.
Palestinian spokesmen said that the two had confessed under torture, but Israeli sources denied that any physical or illegal pressure had been used. Their confessions were borne out by the DNA matches.
"While both suspects grew up in families that were affiliated with the Popular Front for the Liberation of Palestine (PFLP), there is no evidence that they carried out their actions in co-ordination with any organisation," said a senior Shin Bet official. "This was a private initiative and very few people in the village knew about it."
Along with the two alleged murderers, eight other Palestinian civilians were arrested. Among them were four members of Hakim Awad's family, including his father and brother, who had allegedly helped them get rid of the incriminating evidence; and a PFLP member whom they had allegedly approached looking for weapons to carry out the murders.
"In the questioning, they said that their motive was simply to kill Jews and Israelis and to steal weapons to carry out further attacks," said the Shin Bet official. "They said they were perfectly willing to die as Shahids for their cause."