Israel's attorney general, Netanyahu appointee turned accuser
On Sunday, when Netanyahu begins his trial on charges of bribery, fraud and breach of trust, he may well curse the low-key but influential 56-year-old Mandelblit.
Born in Tel Aviv to a right-wing family, Mandelblit is an Orthodox Jew and has six children.
Well respected, he served under Netanyahu as cabinet secretary until 2015, working alongside the premier on a daily basis.
He said he made the decision "with a heavy heart but with a whole heart".
"Law enforcement is not a choice. It is not a matter of right or left. It's not a matter of politics," Mandelblit said at the time.
Before stepping into government roles, Mandelblit was a senior lawyer for the Israeli army.
In 2004, he was named as chief military advocate general and promoted to general five years later.
In that strategic post, he was criticised by right-wingers for conducting investigations against Israeli soldiers suspected of abuses during the 2008-2009 war in Gaza.
In 2014, after he had left the army, he was implicated in the so-called Harpaz affair, named after an officer convicted of producing false documents to influence the appointment of the army's chief of staff.
The investigation into Mandelblit was dropped, with no indictment brought.
- Target of anger -
The most serious involved Netanyahu allegedly offering to change regulatory policies in exchange for favourable coverage from a media outlet.
This faced the attorney general with a difficult decision: whether or not to charge his "boss".
Mandelblit is not expected to attend the opening of Netanyahu's trial on Sunday, although he has been the subject of fierce debate in the days ahead of it.
Rightwinger Netanyahu has long been known for his divisive rhetoric and his supporters have increasingly attacked Mandelblit.
David Amsalem, a minister in Netanyahu's government, has described Mandelblit as an "alleged offender," seemingly referencing the Harpaz affair, in the run-up to the trial.
"Mandelblit is the one taking most of the heat," the Yediot Aharonot newspaper said Friday.
"But by means of the attacks on Mandelblit, they are sending a message to the prosecutor, Liat Ben Ari and to the attorneys working under her, and to the panel of judges".
Mandelblit, who shuns media attention and almost never gives interviews, is unlikely to respond publicly.
He remains an enigma for many commentators who speculate on his political inclinations, but there is little doubt the unassuming figure has become one of Israel's most important and increasingly polarising figures.