It is claimed that in 2005, President Déby held a secret meeting in which he expressed his desire to have Brahim succeed him at some point; this reportedly caused a rift in the family.
On May 24, 2006, Brahim Déby was arrested outside a Paris nightclub after getting involved in a brawl. During the fight, an unlicensed semi-automatic pistol fell from his pocket. Police later searched his house and found 375 grams of marijuana. On June 3, 2006, Brahim Déby was given a six-month suspended sentence for drugs and arms possession.
On July 2, 2007, he was found dead in his apartment building's parking garage in Courbevoie, a suburb of Paris. Due to the apparently violent nature of his death, French authorities are investigating it as murder. An autopsy indicated that Déby, who was covered in white powder, died due to asphyxiation, probably from the powder, which is thought to have been sprayed from a fire extinguisher found near his body. Déby had a wound on his head, but this was thought to be unrelated to his death.
According to a lawyer for Déby's family on July 17, Déby was attacked ten days after arriving in France from Chad; his father had advised him not to return to France due to his past legal issue there. Shortly prior to the attack, Déby was said to be very worried and had received a telephone call, which he did not want to discuss with others. He was attacked by four or five men disguised as policemen who waited for him to arrive at the parking garage. The attackers tazered Déby before killing him by spraying him with the fire extinguisher powder. They then searched his apartment for an unknown reason; it was speculated that the attackers might have been looking for money kept there by Déby.
Déby's body was returned to Chad aboard a specially chartered flight on the morning of July 4. He was buried at midday on the same day in the Muslim cemetery in Lamadji, to the north of N'Djamena. The funeral was held privately but was nevertheless widely attended, with Déby's extended family, as well as government ministers and various political figures, present.