While Carlos remained in Paris and spent his time finding new locations to stash his growing arsenal of weapons, Moukharbal was making regular trips to Popular Front headquarters in Beirut. On June 7 1975, during one such trip, the Lebanese police arrested Moukharbal at Beirut airport, as he was about to board a flight to return to Paris. In his possession they found detailed notes on the movements of several prominent politicians and business identities in Paris and London. Anxious to connect Moukharbal to terrorist activities, the Beirut police asked a former DST officer who was resident in Lebanon, to conduct the interrogation. After questioning the prisoner for nearly two days, Jean-Paul Mauriat, learned that Moukharbal was a member of the Popular Front and worked for a man called George Habash. During the interview, he also mentioned another man he called Nourredine. When asked for further information, Moukharbal told them that the man in question was a "hit man, a killer."

Moukharbal was released on June 13 and put on a plane to Paris, unaware that an undercover Lebanese policeman was tailing him. When the flight arrived in Paris, the Lebanese officer pointed Moukharbal out to a DST team waiting at the airport. Moukharbal was then followed as he caught a cab to Latin Quarter and entered a small apartment building at 9 Rue Toullier. A short time later, Moukharbal left the apartment with a heavily built man with dark hair who carried a suitcase. The DST agents took several photographs of the men but called off the surveillance shortly after.

On June 20, supposedly under constant observation, Moukharbal left Paris and traveled to London. Realizing too late that their man had slipped away, the DST notified London's Special Branch and had him picked up and sent back to Paris. On his arrival at Calais, Moukharbal was taken into custody and questioned by members of the Renseignments Generaux, the French domestic intelligence section. Initially, Moukharbal refused to cooperate with his captors but seven days later, after being threatened with expulsion to Beirut and told that his superiors were not impressed that he had talked to the Lebanese police, Moukharbal cracked and gave them information regarding Nourredine. One piece of information that he did not reveal was the fact that Nourredine was actually his second in command, Carlos.

9 Rue Toullier

He told them that Nourredine often visited 9 Rue Toullier, the home of one of his girlfriends. Acting on the information, Commissaire Herranz and three other officers immediately drove to the address with Moukharbal in the hope that the man might still be there. At the time of their arrival, Carlos was entertaining several Venezuelan students and was partially drunk. When the police knocked at the door of the apartment, Carlos was in the bathroom with one of the girls, showing her an automatic machine pistol, one of the many weapons that he had stashed there.

The police attempted to question Carlos but he resisted  and threatened to call his embassy to complain. The talk became heated and Carlos went back to the bathroom,  retrieved his weapon and slid it down the back of his trousers. Re- entering the room, Carlos offered the policemen drinks and asked one of the women to play a song. The atmosphere in the tiny flat became more relaxed until one of the other police officers entered the room with Moukharbal. When asked if he could identify anyone in the room he raised his arm and pointed at Carlos.

Carlos immediately drew his machine pistol and shot Moukharbal in the neck. Next he swung the gun towards Herranz and shot him, also in the neck. With deadly precision, Carlos shot the two remaining detectives before making his escape into the street via an adjoining apartment. Later, a badly wounded Herranz, was helped into a taxi by two of the students and taken to hospital, he was the only survivor. Incredibly, the attack had been so quick and deadly that the bodies of Moukharbal and the two detectives lay stacked on top of one another. Ironically, prior to the shooting, the French authorities had no knowledge of Carlos or his activities but the eyewitness account, provided by Herranz, gave them enough information to initiate one of the biggest manhunts in history.

Within days of the attack, while the authorities were busy rounding up anyone who had even the slightest connection to him, Carlos made a late night visit to the home of an old girlfriend and retrieved several documents including a Chilean passport that he used to make his escape to Beirut via Brussels.