Experts have found the same DNA on cartridges found at Libération's offices, in the La Défense business district where the SocGen HQ is and on the passenger door of the car that he hijacked to make his escape.
But the genetic imprint does not match any in police records, despite the man's reported claim that he had just come out of prison.
Police have received more than 700 calls from the public and taken in several people for questioning without finding the perpetrator.
Several hundred officers are on his trail, according to Interior Minister Manuel Valls, who warned that "it takes time" to solve such a case.
Reported sightings of an armed man in the south-western city of Périgueux on Tuesday turned out to be a false alarm.
After several residents told police they had seen a man with his face covered toting a rifle in the centre of town, police examined CCTV footage and found that the weapon was a fake of the type used in paintball games.
The four photos taken from CCTV cameras in Paris justify videosurveillance, the right-wing candidate for Paris mayor, Nathalie Kosciusko-Morizet, said Wednesday, claiming that the majority of her Socialist opponents have misgivings at the spread of security cameras.