A 65-year-old woman was arrested on Monday after death threats and bullets were sent by mail to Israeli Prime Minister Naftali Bennett’s family.
Police said a woman from southern Israel was being questioned over the threats to the Bennett family last month.
They received two death threats, along with the bullets.
Security around the premier and his family was tightened in response to the threats and police and the Shin Bet internal security agency opened an investigation.
Mr Bennett, who leads a small nationalist party, has come under intense criticism from Israeli hardliners who accuse him of abandoning his ideology, AP reported.
In 1995, Prime Minister Yitzhak Rabin was assassinated by a Jewish ultranationalist opposed to his attempts at making peace with the Palestinians.
Mr Bennett leads a narrow coalition of eight parties ranging from a small Islamist party to Jewish ultra-nationalists that have little in common beyond their opposition to former Prime Minister Benjamin Netanyahu.
His government was formed after four inconclusive parliamentary elections that highlighted deep divisions in Israeli society over relations with the Palestinians, religion and state, and Mr Netanyahu’s fitness to rule while on trial for corruption.
In the aftermath of 11 days of deadly fighting with Palestinian militants in the Gaza Strip in May last year, Mr Bennett finally agreed to join centrist Yair Lapid in a coalition to oust the prime minister, who had been in power for 12 consecutive years as well as an earlier three-year term.