Police on Tuesday followed a woman they knew had links to the suspected mastermind of the Nov. 13 Paris attacks and watched her take him into the building that special forces attacked early the next morning, a police source told Reuters.
French police had been tapping the phone of Hasna Aitboulahcen as part of an investigation into potential drug offences and were able to track her down in the St. Denis suburb north of the French capital.
She detonated a suicide belt early on Wednesday during the seven-hour police assault on the building.
Sources say she may be the cousin of Abdelhamid Abaaoud, who is believed to have coordinated the attacks in Paris that killed at least 129 people. Abaaoud also died in Wednesday's police raid, along with a third, unidentified person.
"A physical surveillance took place which allowed us to establish that the young woman and the jihadist went into the building in Rue Corbillon in St. Denis on Tuesday early in the evening," the source said, declining to be identified because he is not authorized to speak officially.
According to the source, after police learned that Abaaoud was in France and not in Syria as they previously thought, they set out to find Aitboulahcen in the hope he may be with her.
Moroccan security officials provided information that helped their French counterparts launch the raids in the Paris suburb, a Moroccan source said earlier this week. Aitboulahcen and Abaaoud are both of Moroccan origin.
According to the police source, its was these Moroccan officials who told the French authorities Abaaoud was in France.
The king of Morocco was on a visit to France on Thursday.