Mohammed Merah, 24, was on the U.S. no-fly list because he had been in custody in Afghanistan in 2010 before being sent back to France, sources familiar with the case told the newspaper.
The circumstances of Merah's detention in Afghanistan were not clear, and the Journal said U.S. officials said there was no record of him ever being in the custody of the American military.
Merah was also named as a member of a group called Forsane Alizza, or Knights of Glory, French Interior Minister Claude Gueant said. The French government banned the group in January for trying to recruit people to fight in Afghanistan.
Merah's career in terrorism came to an end Thursday when he was fatally shot while jumping out of a window in an apartment house in Toulouse by a police tactical team. Police had surrounded the building for more than 30 hours.
Merah reportedly admitted he had carried out the drive-by shootings in southern France that left seven people dead. The victims included three French soldiers gunned down last week and four people, including three children, killed at a Jewish school in Toulouse Monday.
The Los Angeles Times said Merah made video recordings of last week's shootings, which were in the hands of police. Toulouse prosecutor Francois Molins told reporters Merah said to one paratrooper "You kill my brothers; I kill you" as he opened fire.
Investigators Thursday were looking into any potential accomplices Merah may have had. The Journal said the gunman's older brother and mother were in custody, but prosecutors did not say why.