Credit Charles Platiau/Reuters
PARIS — The gunman who killed a police officer Thursday evening on the Champs-Élysées in Paris had been detained in February for making threats, but he was released because there was not enough evidence to charge him, according to French news reports and The Associated Press.
The Islamic State militant group claimed responsibility within hours of the attack, which also wounded two police officers and a bystander. The attack briefly shut down the city’s most famous boulevard and deeply unsettled France just days before voting on Sunday in the first round of the presidential election.
On Friday, the office of the Paris prosecutor, François Molins, disclosed that the authorities had found a pump-action shotgun, two large kitchen knives, a pair of pruning shears and a Quran had been found in the gunman’s car.
The prosecutor’s office also said that three people linked to the gunman had been taken into custody for questioning.
The office would not confirm numerous reports in the French news media that the gunman had a criminal record. According to The A.P., the gunman was detained in late February after speaking threateningly about the police, but he was released for lack of evidence. He was convicted in 2003 of attempted homicide in the shootings of two police officers, The A.P. reported.
Mr. Molins was expected to hold a news conference later on Friday.