A list of targets, including journalists and the police, was found in the house of the police officer who was stabbed to death on Monday night by an Islamic State (IS)-linked man, Paris Prosecutor Francois Molins said on Tuesday.
Three phones, three knives, including the one with blood placed on the table, were found in the house of the police officer, Xinhua quoted Molins as saying.
The prosecutor also said the assailant, Larossi Abballa, admitted to the police that he pledged allegiance to the IS three weeks ago and acknowledged the victim's status as police officer.
Larossi Abballa was arrested in 2011 and sentenced to three years in prison in 2013 for helping terrorists to go to Pakistan.
So far, three people have been arrested and placed in custody during the double murder investigation.
The police officer was stabbed to death by the suspect on Monday night in the west Paris suburb of Magnanville. His partner was also killed at their home.
Hours after the attack, an IS-linked news agency report said that the attack was carried out by an "Islamic State fighter".