The police and the Shabak believe that the person who sent the death threat to the family of Prime Minister Naftali Bennett is familiar with the daily routine of the family, Channel 13 News reported.
The investigation also shows that the threats were explicit and aimed at the prime minister's wife, Gilat, and his eldest son, Yoni Bennett, who is relatively exposed because of his activities on social media.
It was further revealed that the threatening letter read: "We can reach you."
The police and Shabak are attempting to make contact with the person who sent the letter, which came with a bullet in the envelope.
Prime Minister Bennett said in response to the threatening letter: "Political conflict, no matter how deep it is, should not reach violence, bullying and death threats. We need to do everything, as leaders and as citizens whose future and the future of their children in this country, so that such phenomena simply do not exist. We are all people. Arguments and disagreements - yes. Bullying and threats - no.
"I am a prime minister and a political man, but I am also a husband and father, and it is my duty to also take care of my wife and children. We must lower the flames of political discourse," he said.
"On the eve of Memorial Day and Independence Day, I call on everyone - from all corners of the political spectrum, especially people who are active on social media - to have this be a time of calm and reconciliation."