Deby was a strongman, hailed by his allies but despised by his people. Experts say his death leaves behind a country torn apart, a region plagued by extremist groups and his Western allies unsure of how to proceed.
Idriss Deby Itno was the man in charge of Chad's counterterrorism operations in the Sahel and the Lake Chad Basin. Back home, he also had a reputation for ruling with an iron fist.
The demise of Chad's president of 30 years undoubtedly has implications for the stability of the Central African nation, as well as its neighbors.
Observers have already cried foul over the army's decision to set up a transitional military council headed by Deby's son and former head of the presidential guard, Mahamat Idriss Deby Itno.
The country's constitution stipulates that should a head of state die while in office, the president of the National Assembly will lead the country for a brief provisional period before fresh elections can be held.
But allies of the late president moved quickly to ensure they retained power. Under a new "Transition Charter," Mahamat Deby will "occupy the functions of the president" and serve as the head of the armed forces for 18 months.
Meanwhile, neighboring Nigeria on Thursday beefed up its border security to avoid a sudden influx of Chadians seeking to escape from their home country. As rebels advance towards the capital, N'djamena, the conflict-ridden country is evidently on a dangerous path.
Death rumors persist
Amid the confusion, some observers have been swift to point out that the circumstances surrounding Deby's death remain suspiciously unclear. On April 20, it was announced that the 68-year-old president had succumbed to injuries sustained on the battlefield between state forces and rebels.
Former minister Faustin Facho Balaam, who has lived in exile since 2008, does not believe Deby died in battle as first reported.
"Deby was killed by people from his own circle," he told DW. "He had become unbearable and the military did not want to fight the rebellion... I think it is a coup d'etat, not a death on the front line."
A country in crisis
The timing of Deby's death doesn't help matters either. Just a day before the news of his demise was announced, Chad's electoral commission confirmed that Deby had won the April 11 presidential election that would usher him into his sixth term in office.
Deby was criticized during the election period for cracking down on the opposition and shutting down the internet. The political-military group, Front for Change and Concord in Chad (FACT), which is based in the country's north, had called for Deby to resign and started moving towards the capital.
FACT, which was founded by dissident army officers in 2016, went on to attack a military post, sparking clashes with state forces in the western Kanem province, where Deby was reportedly killed on the battlefield.
DW West Africa correspondent Fred Muvunyi says Deby's death leaves Chad in a very precarious situation.
"Already the country was in a crisis, the opposition boycotted the election, a rebel group attacked the country from Libya," he says. "Insecurity, poverty, joblessness and hardship after Deby's 30-year leadership without any concrete promises ... The worry now is the way forward."
With no fewer than 2,500 soldiers fighting Islamic extremists in the Sahel and Lake Chad Basin, Chad's impeding implosion is expected to seriously worsen security in the region.
Malian lawyer and former Secretary of State for Justice Mamadou Ismaila Konate says the impact of Deby's death on the security situation in the Sahel shouldn't be underestimated.
"Chad has been attacked from all sides by rebel organizations who want nothing but to overthrow Deby's regime," he told DW. "The Sahel zone is also [home to] the regional alliance G5 Sahel, with a strong presence of the Chadian army."
Starting a new chapter?
Despite these concerns, journalist and Chad expert Seidick Abba hopes that the death of Chad's long-time president may present a chance for a fresh start after years of conflict and instability.
"In my opinion, Chad now has the opportunity to open a new chapter after the Deby years and to engage in dialogue -- I heard that the military would be open to it -- to shape the transition," he says.
Abba believes that for the transition to work, Mahamat Deby would need to build a consensus with Chad's political forces and map out a timeline for a proper transition that would end with democratic elections.
"We have to consider the timetable for the real transition, for free and democratic elections," he says. "For me, that should be the interest of Deby's son and the greatest interest of Chad."
France watching former colony closely
Observers in France are also watching to see how events unfold in the wake of Deby's death.
On Thursday, the former colonial power officially backed the new leadership in Chad despite concerns over its constitutionality.
French Foreign Minister Jean-Yves Le Drian defended the military takeover saying it was necessary for security.
"There are exceptional circumstances," he said. "Logically, [the new leader] should be [Prime Minister Haroun] Kabadi...But he refused because of the exceptional security reasons that were needed to ensure the stability of this country."
The former colonial power has maintained a consistent military presence in Chad since 1986 and is currently involved in the ongoing anti-insurgent operation, Operation Barkhane. However, France has also been blamed for failing to protect Chad's quasi-democracy over the years.
"France has supported Idriss Deby since he came to power, primarily through military and diplomatic support," says Emma Cailleau from the NGO Survie, which has often taken a critical stance over French neo-colonialism in Africa.
Cailleau says Deby was considered a vital ally in the fight against terrorism.
"As such, he had a considerable diplomatic and military income, with influence over the entire international community," she explains.
What Deby's exit from the leadership stage truly means for Chad and its Western allies remains to be seen. But as Mali's former Secretary of State Mamadou Ismaila Konate points out, Deby's death in many ways mirrored his leadership.
"Of course we cannot celebrate the death of a leader," he says. "But it is clear that the rule that says 'whoever rules by the sword will perish by the sword' applies to Idriss Deby."