Friends and family of the five members of the same family who were slain last March in one of the most shocking atrocities in Israeli history have marked the first yartzheit of their deaths.

Udi and Ruth Fogel, and three of their children, including three-month-old Hadas Fogel, were found dead at their home on Friday March 11 2011.

Their bloodied bodies, including that of Hadas, who had been decapitated, were discovered by the eldest daughter Tamar, then 12.

Yesterday marked a year on the Hebrew calendar since the massacre, carried out by two Palestinian men. In Itamar thousands, including Knesset Speaker Reuven Rivlin, gathered for the dedication of a new Beit Hamidrash (study hall) named in honour of Mr Fogel.

Haim Fogel, Tamar's grandfather, told the crowd that the task was "to fill this place with students who will continue Udi and Ruth's legacy".

He said: "A year has passed since the catastrophe, a difficult year of memories and nostalgia, of soul searching among public and private grief."

Israeli President Shimon Peres sent a letter of condolence to the surviving members of the family. He said: "Parents and their young children that were cruelly slaughtered in cold blood at their home in Itamar on the eve of the Sabbath.

"The year that has passed since that shocking day cannot dull, even a little, the awful pain, the yearning and the sorrow."