Once tipped as a successor to Iran's supreme leader, President Ebrahim Raisi had swiftly risen through the ranks before his untimely death at the age of 63.

Born in Mashhad on Dec. 14, 1960, Raisi was born into a family that traces its lineage to Islam's Prophet Muhammad, marked by the black turban he would later wear.

His father died when he was 5, but followed his footsteps to become a cleric. He attended a seminary in the Shiite holy city of Qom and later would describe himself as an ayatollah, a high-ranking Shiite cleric.

As a young student, Raisi took part in protests against the Western-backed Shah in the 1979 revolution. Later, his contacts with religious leaders in Qom made him a trusted figure in the judiciary.

As a young prosecutor in Tehran, Raisi sat on a panel that is accused of overseeing the execution of hundreds of political prisoners in the capital in 1988, as Iran's eight-year war with Iraq was coming to an end, rights groups claim.

Asked about allegations that he had played a part in the death sentences, Raisi told reporters in 2021: "If a judge, a prosecutor, has defended the security of the people, he should be praised ... I am proud to have defended human rights in every position I have held so far."

He served as deputy head of the judiciary for 10 years before being appointed prosecutor-general in 2014. Five years later, the U.S. imposed sanctions on him for human rights violations, including alleged executions in the 1980s.

Raisi eventually rose through the ranks of Iran's Shiite Muslim clergy and was appointed by Khamenei to the high-profile job of judiciary chief in 2019.

Shortly afterward, he was also elected deputy chairman of the Assembly of Experts, the 88-member clerical body responsible for electing the next supreme leader.

Elected president in a closely controlled vote in 2021, Raisi took a tough stance in the nuclear negotiations, seeing a chance to win broad relief from U.S. sanctions in return for only modest curbs on Iran's increasingly advanced technology.

In 2018, then-U.S. President Donald Trump had reneged on the deal Tehran had made with the six powers and restored harsh U.S. sanctions on Iran, prompting Tehran to progressively violate the agreement's nuclear limits.

Indirect talks between Tehran and U.S. President Joe Biden's administration to revive the deal have stalled.

Although a political novice, Raisi had full backing for the nuclear stance and the security crackdown from his patron, the strongly anti-Western Supreme Leader Ayatollah Ali Khamenei.

Raisi shared with Khamenei a deep suspicion of the West. An anti-corruption populist, he backed Khamenei's self-sufficiency drive in the economy and his strategy of supporting proxy forces across the Middle East.

Khamenei, rather than the president, has the final say in all major policies under Iran's dual political system, split between the clerical establishment and the government.

Raisi's hardline position was also evident in domestic politics. A year after his election, the mid-ranking cleric ordered tighter enforcement of Iran's "hijab and chastity law" restricting women's dress and behavior.

Within weeks, a young woman Mahsa Amini died in custody after being arrested by morality police for allegedly violating that law.

The resulting months of nationwide protests presented one of the gravest challenges to Iran's clerical rulers since the 1979 Islamic Revolution.

Hundreds of people were allegedly killed, according to rights groups, including dozens of security personnel who were part of a fierce crackdown on the demonstrators.

Raisi's election victory, after heavyweight conservative and moderate rivals were disqualified by a hardline oversight body, brought all branches of power in Iran under the control of hardliners loyal to Khamenei and bolstered Raisi's chances of one day succeeding him as Supreme Leader.

However, the widespread protests against clerical rule and a failure to turn around Iran's struggling economy – hamstrung by Western sanctions and mismanagement – may have diminished his popularity at home.

When a missile attack killed senior Iranian Revolutionary Guard officers in Iran's embassy in Damascus last month, Iran responded with an unprecedented but largely unsuccessful direct aerial bombardment of Israel.

He said that any Israeli retaliation against Iranian territory could result in there being nothing left of the "Zionist regime."

Raisi died when a helicopter carrying him back from a visit to the Azerbaijani border crashed in mountainous terrain, killing all aboard, a senior Iranian official said. Foreign Minister Hossein Amirabdollahian was among those killed.