3 Paris Attack Suspects Already known

At least three people believed linked to Friday's Paris terror attacks were previously known to Belgian authorities, Belgian prosecutor Eric Van Der Sypt told CNN on Tuesday.

Two of those three suspects are dead and one remains at large. Ibrahim Abdeslam reportedly blew himself up in the attacks. Bilal Hadfi was one of the suicide bombers who struck outside the Stade de France, according to several sources. And Abdeslam's 26-year-old brother, Salah Abdeslam, is the target of an international manhunt.

Van Der Sypt told CNN's Ivan Watson that police questioned the Abdeslam brothers in February.

"Ibrahim tried to go to Syria and was sent back by the Turks in the beginning of 2015," Van Der Sypt said. "It was after that that we questioned him." Both brothers were released, the federal prosecutor said, after they denied wanting to go to Syria.

He said Belgian authorities were also trying to keep an eye on Hadfi. "We knew he was in Syria," Van Der Sypt said. "But what we didn't know is apparently he was back, as he blew himself up in Paris. But we had no knowledge of the fact that he was back in Europe."

A black Renault Clio found in Paris' 18th district Tuesday morning had been rented by Salah Abdeslam, multiple French media outlets reported, citing police sources.

Before the Paris attacks, France and its allies had tried to target a prominent ISIS member who is believed to have planned the assault on the French capital, a French source close to the investigation said.

Western intelligence agencies had attempted to track Abdelhamid Abaaoud, a Belgian citizen thought to be in Syria, but they weren't able to locate him, the source told CNN on Tuesday.

Abaaoud had been implicated in the planning of a number of terrorist attacks and conspiracies in Western Europe before the Paris attacks. ISIS claimed responsibility for the slaughter, in which men armed with assault rifles and suicide vests killed at least 129 people and wounded hundreds more.

Believed to be close to ISIS leader Abu Bakr al-Baghdadi, Abaaoud was linked to a plan to attack Belgian police that was thwarted in January. He has since been featured in ISIS' online English-language magazine. His current whereabouts are unknown.