The official told The Associated Press that there is no sign that Mohamed Merah had "trained or been in contact with organized groups or jihadists." The official spoke Friday on condition of anonymity because of the sensitivity of the investigation.
The 23-year-old had traveled to Afghanistan and Pakistan and claims he had been in contact with al Qaeda. A little-known jihadist group called Jund al-Khilafah claimed responsibility for the killings on Thursday, but the official said the claim seemed opportunistic. The claim has yet to be independently confirmed.
Merah was killed in a gunfight with police on Thursday following a 32-hour standoff.
He was wanted in the deaths of three French paratroopers, three Jewish schoolchildren and a rabbi - all killed since March 11. Police found evidence inside his apartment that he videotaped all of the killings.
Before he died, Merah allegedly told negotiators he committed the killings to avenge the deaths of Palestinian children and to protest the French army's involvement in Afghanistan as well as France's law against the Islamic face veil. He showed no remorse for the killings and told authorities his only regret was that he did not have time to kill more people.
French President Nicolas Sarkozy has promised a full investigation to see if Merah had accomplices to help him carry out his killing spree. Investigators were questioning Merah's brother in connection with the killings, which is France's worst Islamist terrorist violence since a wave of attacks in the 1990s by Algerian extremists.
The Associated Press contributed to this report.