As the clock ticks down Tuesday on the 96 hours French police are allowed to detain terror suspects, France waits to learn the fate of 12 people held in Paris. Authorities dismantled what is believed to have been an Islamist cell in weekend raids across the country that left one dead. Jérémie Louis-Sidney, wanted in connection with an attack on a kosher grocery near Paris, was shot dead by police on Saturday after allegedly firing all six rounds of his .357 Magnum at police when they forced open his door in Strasbourg. Authorities have until Wednesday morning Paris time to hold the suspects without charge.

On Sept. 19, a grenade attack targeted a kosher grocery in Sarcelles, a multi-ethnic suburb north of Paris, injuring one. Police say Louis-Sidney’s DNA was found on the safety catch of the Yugoslavian-model grenade. An ex-convict nicknamed “James,” Louis-Sidney, 33, was a convert to Islam and known to French intelligence authorities for his suspected jihadist sympathies. Twelve suspects, all French citizens born in France, primarily in the ’80s and ’90s, were arrested Saturday in Strasbourg, Cannes, and the Greater Paris area. Police seized weapons, more than 27,000 euros in cash, a list of Paris-area Jewish organizations, and several wills in related home searches. Two of the wills were reportedly completed and signed—one by Louis-Sidney, another by Yann Nsaku, 19, a Muslim convert whose fledgling soccer career at English club Portsmouth’s youth team was cut short by a knee injury last year. Nsaku is among the 12 suspects detained.

The Sarcelles kosher grocery attack occurred on the same day that a French satirical newspaper published lewd cartoons of the Prophet Mohammad in the wake of violent global protests against an anti-Islam film, and six months to the day after “Scooter Killer” Mohamed Merah killed a rabbi and three children at a Jewish school in Toulouse. The new incident rattled France’s Jewish community, Europe’s largest, after Jewish community groups had already expressed concerns that anti-Semitic incidents increased in the aftermath of the Toulouse killings.

In March, Merah, 23, killed seven people—the four victims at the Ozar Hatorah school and three French soldiers, two of whom were Muslim, in two prior incidents. After a manhunt that captivated the nation and a 32-hour standoff at his Toulouse home, Merah was shot dead by police on March 22, a month before the first round of presidential elections that would see incumbent Nicolas Sarkozy lose to François Hollande. A wide cross-section of observers—including Latifa Ibn Ziaten, the hijab-wearing mother of one of Merah’s soldier victims—have since fretted about Merah’s status as a martyr or hero to some in France’s troubled banlieues.

The new arrests have rekindled fears about the potential threat of young French Muslims—sometimes converts to Islam—tempted to perpetrate attacks after tipping into extremism. And it has reignited the debate about insufficient numbers of Muslim chaplains in French prisons to counter the spread of radical Islam behind bars. In the case of past attacks on French soil by Islamic extremists, perpetrators’ prior prison stays have sometimes been tipped as factors in their radicalization. Merah did time before he sought out terrorist training camps in Waziristan. Jail time was also thought to be a factor in the radicalization of Khaled Kelkal, an Algerian-born, French-raised 24-year-old implicated in a wave of deadly terrorist attacks in France in 1995 before he was shot dead by gendarmes. However, it remains unclear that Louis-Sidney’s purported turn to extremism dates to the relatively brief jail time he served in a drug case in 2008.

In early excerpts of an exclusive interview slated to appear Thursday in the French weekly Paris Match, Interior Minister Manuel Valls claims trips to Tunisia or Egypt played a role in the path taken by the suspected extremists arrested on Saturday. “It appears that some of them had planned to go fight in Syria,” Valls tells Paris Match. “We must therefore improve the capacity to follow these itineraries.” French authorities in the Toulouse affair were heavily criticized for appearing to lose track of Merah before his deadly spree, despite knowledge of his travels to Pakistan and Afghanistan. Valls’s comments to Paris Match can be interpreted in that light when, citing “rapid action,” he calls “taking the least risk” of letting suspect individuals act out their plans “out of the question.”

Valls, a Socialist cabinet minister with a tough-on-crime image, has been a star in the fledgling French administration under Hollande, earning favorable poll numbers among left- and right-wingers alike even as Hollande’s approval ratings have slumped badly. In an Ipsos survey conducted in part, as it happens, on Saturday as the net came down on the Islamist suspects, Valls was named France’s favorite political personality, with 57 percent holding a favorable opinion of him, up seven points over the past month. Yet another incentive for a French government in need of a boost not to be seen going soft on terror.