Those interviews all pointed to a decisive intervention behind the scenes by Sistani, who has never held formal political office in Iraq but presides as the most influential scholar in its Shiite religious centre, Najaf.
According to the officials, Sistani's office ensured Sadr understood that unless Sadr called off the violence by his followers, Sistani would denounce the unrest.
“Sistani sent a message to Sadr, that if he will not stop the violence then Sistani would be forced to release a statement calling for a stopping of fighting — this would have made Sadr look weak, and as if he'd caused bloodshed in Iraq,” said an Iraqi government official.
Three Shiite figures based in Najaf and close to Sistani would not confirm that Sistani's office sent an explicit message to Sadr. But they said it would have been clear to Sadr that Sistani would soon speak out unless Sadr called off the unrest.
An Iran-aligned official in the region said that if it were not for Sistani's office, “Moqtada al-Sadr would not have held his press conference” that halted the fighting.
'BETRAYAL'
Sistani's intervention may have averted wider bloodshed for now. But it does not solve the problem of maintaining calm in a country where so much power resides outside the political system in the Shiite clergy, including among clerics with intimate ties to Iran.
Sistani, who has intervened decisively at crucial moments in Iraq's history since the US invasion that toppled Saddam Hussein, has no obvious successor. Despite his age, little is known publicly about the state of his health.
Meanwhile, many of the most influential Shiite figures — including Sadr himself at various points in his career — have studied, lived and worked in Iran, a theocracy which makes no attempt to separate clerical influence from state power.
Last week's violence began after Ayatollah Kadhim al-Haeri, a top ranking Iraqi-born Shiite cleric who has lived in Iran for decades, announced he was retiring from public life and shutting down his office due to advanced age. Such a move is practically unknown in the 1,300-year history of Shiite Islam, where top clerics are typically revered until death.
Haeri had been anointed as Sadr's movement's spiritual adviser by Sadr's father, himself a revered cleric who was assassinated by Saddam's regime in 1999. In announcing his own resignation, Haeri denounced Sadr for causing rifts among Shi'ites, and called on his own followers to seek future guidance on religious matters from Ayatollah Ali Khamenei — the cleric who also happens to rule the Iranian state.
Sadr made clear in public that he blamed outsiders — implicitly Tehran — for Haeri's intervention: “I don't believe he did this of his own volition,” Sadr tweeted.
A senior Baghdad-based member of Sadr's movement said Sadr was furious. “Haeri was Sadr's spiritual guide. Sadr saw it as a betrayal that aimed to rob him of his religious legitimacy as a Shiite leader, at a time when he's fighting Iran-backed groups for power.”
Sadrist officials in Najaf said the move meant Sadr would have to choose between obeying his spiritual guide Haeri and following Khamenei, or rejecting him and potentially upsetting older figures in his movement who were close to Sadr's father.
Instead, Sadr announced his own withdrawal from politics altogether, a move that spurred his followers onto the street.
The Iranian government and Sadr's office did not immediately respond to request for comment for this story. Haeri's office could not immediately be reached.
Specialists in Shiite Islam say Haeri's move to shut his own office and direct his followers to back the Iranian leader would certainly have appeared suspicious in an Iraqi context, where suggestions of Iranian meddling are explosive.