Rafsanjani's daughter, Faezeh Hashemi, a political activist and former member of Parliament, was taken to Tehran's notorious Evin prison Saturday to serve a six-month sentence after being found guilty of "spreading propaganda against the regime."
On Monday, her brother, Mehdi Hashemi, was seized on charges of anti-state activity when he reported to the state prosecutor's office in Tehran for interrogation the day after he returned from a self-imposed three-year exile in London. He too was taken to Evin.
This kind of pressure on a former president "is unprecedented in the history of the Islamic Republic, especially for Rafsanjani, who is believed to have played an instrumental part in the appointment of Ayatollah Ali Khamenei as the supreme leader after the death in 1989 of the Islamic revolution's founder, Ayatollah Khomeini," observed Iranian analyst Saeed Kamali Dehghan.
Hashemi, Rafsanjani's son, fled Iran in 2009, apparently to evade prosecution for alleged involvement in massive protests after the bitterly disputed presidential election that gave President Mahmoud Ahmadinejad a second term.
Thousands of protesters, and several well-known critics of Ahmadinejad, were arrested in a nationwide crackdown.
The 78-year-old Rafsanjani, who served two terms as president in 1989-97, has long been seen as a moderate, particularly when compared to the hard-liners in the Iranian regime.
But he remains an influential voic, and presides over the Expediency Council which mediates between the 290-seat Majlis, Iran's Parliament which is increasingly critical of Ahmadinejad, and the Guardian Council, a powerful body that vets all legislation.
However, Rafsanjani has of late distanced himself from reformist leaders such as Mir Hossein Mousavi and Mehdi Karroubi, both of whom are under house arrest.
That suggests he may be seeking a low profile in the run-up to the presidential elections scheduled for June 14.
He has long opposed the radical Ahmadinejad, who is locked in a power struggle with Iran's supreme leader, Ayatollah Ali Khamenei, and the diehard conservatives who surround him.
Ahmadinejad defeated Rafsanjani in the 2005 presidential election after a bitter contest. Ahmadinejad won largely because Khamenei backed the former Revolutionary Guards hero of the 1980-88 war against Iraq.
Khamenei has come to regret that decision as Ahmadinejad and his coterie of radicals have challenged the conservative clerics' hold on power.
Under Iran's constitution, Ahmadinejad must step down at the end of his second term but he appears determined to ensure that one of his followers succeeds him -- and that's where Rafsanjani may come in to undercut his old rival.
Admittedly, Rafsanjani's authority has dwindled since his 2005 defeat. Pressure on him and his family has been growing.
His other son, Mohsen, resigned under pressure from Ahmadinejad's regime as head of Tehran's metro organization in 2011.
Indeed, there has been considerable speculation that one of the corps' top officers, Maj. Gen. Qassem Suleimani, may throw his hat in the ring in June, a move that would be seen as a bid by the Guards to take political power.
If Rafsanjani chooses to run for president, possibly with Khamenei's blessing this time, he could have to run against Suleimani, commander of the Guards' elite al-Quds Force, a formidable foe.
And the Guards control the Basij, the million-man strong militia the regime has used to enforce its will and clobber those who oppose it.
Suleimani's star is high because of the success of the Al-Quds Force, the Guards' covert operations arm, in fighting the Americans in Iraq, supervising Hezbollah in Lebanon and helping embattled Syrian President Bashar al-Assad, a strategic Tehran ally, hold onto power.
Rafsanjani has also been hurt by allegations of corruption over the last decade or more. In that, he's no different that most of the Iranian elite but it's the kind of mud that sticks and could prove costly in a presidential race.
"Despite all the setbacks, Rafsanjani still has relatively good influence among supporters of the regime, albeit not necessarily with those in power." one Tehran analyst observed.
"As a moderate figure he can still be considered as Iran's way out of the current stalemate with the international community."