On Thursday, he met up with his uncle in Gaafour, catching up on family matters, on a break from his master’s studies in the nearby historic town of Kairouan.
A day later, Resgui walked calmly though the Imperial Marhaba beach hotel on Tunisia’s Mediterranean coast opening fire with a Kalashnikov, and in more than five minutes slaughtered 39 foreign tourists in the name of Islamic State.
Once again, Tunisia is in shock over how one of its young men with little warning turned from what appeared to be a normal life to hardline violent ideology of Islamic jihad.
Again, a well-educated Tunisian from a middle class family appears in a short time to have fallen prey to radical recruiters who turned him away from a life of soccer and music to become a militant Islamist.
In Gaafour, an isolated farming town on the arid plains southwest of Tunis, neighbors and family struggle to piece together how a neighborhood favorite and son became a killer responsible for the country's worst militant attack.
Authorities and witnesses say Rezgui was the only gunman who opened fire on the beach of the Imperial Marhaba, working his way through the pool, and hotel reception picking out foreigners, before he was shot himself by police.
Just as with the two young Tunisians who attacked the Bardo museum in Tunis in March, killing 21 people, Saif gave little hint to family and friends of his new radical beliefs. If anything he revealed nothing at all.
A fan of break-dance, rap music and most of all Club Africa, Tunisia's league champions, Rezqui worked part time in the small Ben Hassan café in Gaafour serving coffee and cigarettes.
"Who could imagine he would commit such a horror?" Ali Rezgui, his uncle, told Reuters, slumped in a plastic chair outside the modest one-story white house where the family gathered to mourn.
"Maybe he was changed where he studied, maybe it was something on the internet. But we just don't have any answers."
The Bardo killers -- one from a similar rural town as Gaafour; the other from Tunis -- were both recruited by hardline preachers at their mosques. Both spent time in Libya at training camps before their attack.
How Rezgui fits into this current is still unclear. There was little clue at all he had been recruited. Gaafour’s mosque is not linked to any ultraconservative Islamists.
He was studying in Kairouan which, with its famous Great Mosque, after the 2011 revolution become a hub for hardline Islamist groups such as Ansar al-Sharia.
But authorities say Rezgui was not on any terrorism watchlist or known to associate with hardline Islamists. He was not known to police as a suspect. Security sources said he appeared to have been radicalized just over the last six months.
"He was in contact with extremists outside of Tunisia, through the internet," one security source said.
Forensic evidence shows that all the bullets at the beach resort massacre were fired from the Kalashnikov Rezgui used in the attack, indicating he was the only attacker, the source said.
Rezgui may have acted alone as a so-called "Lone Wolf" jihadist more inspired by Islamic State's jihadist message than associated directly with the militant group. But he kept his secret life well-hidden.
"It's hard to believe. I really can't comprehend it," said Ahmed, who danced in a break-dance group with Rezgui. "When I saw his image with the Kalashnikov, I just keep thinking of how we had just been together."