The source said that investigators had analyzed the suicide belt, found on a sidewalk on rue Frederic Chopin in the Paris suburb of Montrouge, and discovered traces of sweat that matched Abdeslam's DNA.
Investigators are working under the theory the Belgian-born French national was supposed to blow himself up in Paris' 18th arrondissement but backed out, the source told CNN.
In an ISIS
statement claiming responsibility for the November shootings and bombings in the French capital, the terrorist group referred to an attack in the 18th district -- but none is known to have taken place there.
The day after the suicide belt's discovery, Paris prosecutor Francois Molins said at a news conference an investigation was ongoing as to whether Abdeslam was planning a suicide attack in the 18th, and, if so, why it didn't happen.
On the night of the November 13 attacks, Abdeslam dropped suicide bombers off at the Stade de France and then drove to the 18th before authorities later traced his phone signal to Montrouge, Molins told the press conference.
Investigators have been looking for Abdeslam since shortly after the attacks, which killed 130 people
, and sources close to the investigation have speculated he may have fled to Syria.
Terror suspects questioned
The latest revelations came shortly after French authorities revealed they were questioning three people in relation to terror attacks in the capital.
Two suspects were being held as part of the investigation into January's deadly siege of a kosher grocery store in the Paris suburb of Vincennes, a representative for French prosecutors told CNN.
Separately, a 29-year-old man was arrested Tuesday morning in connection with the November attacks, according to a representative for the same office.
It wasn't immediately known if the deadly terrorist attacks, or the arrests, are related.
The kosher market attack happened in the tense, frenetic days following the massacre at the Paris office of the Charlie Hebdo
satirical magazine. Amedy Coulibaly
stormed the Hyper Cacher market January 9, killing four people and taking others hostage before police killed him.
The prosecutor's office representative identified the pair being held in that case as Claude Hermant and his wife, both of whom are accused of being involved in arms trafficking.
Hermant has been held since January in an arms trafficking investigation. French media outlets have identified him as a well-known figure in far-right circles, particularly in the northern city of Lille, reporting that he was a former soldier who had worked as part of the security detail for the anti-immigration National Front political party
There's no evidence of a direct connection between the couple and Coulibaly, but some weapons found in Coulibaly's arsenal are thought to have come from Hermant or his wife, through a company she managed, according to the Paris prosecutor's representative.
Hermant was picked up from his jail cell in the Lille region, which is also the area where his wife was apprehended.