Mr Kelkal's photograph and details were circulated at the weekend together with a report saying that his fingerprints had been found on the unexploded bomb planted on the high-speed train line near Lyons last month. Police sources said they had information that he had been staying until very recently at a hostel for the young homeless near Grenoble.
The Justice Ministry said the purpose of the raids had been to search addresses which "could serve as refuges for members of networks linked to the Armed Islamic Group", believed to be responsible for recent bomb attacks in Paris and Lyons. But the official emphasis on the participation of several police and intelligence branches suggests the raids may also have been a response to criticism voiced by President Jacques Chirac on Sunday, when he spoke of "disorder" in the anti-terrorist investigation.
The identification of Mr Kelkal had already represented a step forward: it was the first time a named suspect had been linked with any of the six bomb attacks by material evidence.
Casting the spotlight on Mr Kelkal also illuminates an aspect that the authorities probably hoped to leave in obscurity: the extent to which certain suburbs of certain large cities with large North African populations have become breeding grounds for Islamic fundamentalism.
Mr Kelkal, although born in Algeria, had all his schooling near Lyons. His intelligence and stable family background are said by one of his teachers to have marked him out from many of his contemporaries, and he qualified for a good lycee, where he studied for the equivalent of A-levels, specialising in chemistry. In time, he became involved in petty crime; in 1991 he was sentenced to four years for ramraiding. Thereafter, he seems to have been lost to the mainstream of society.
His biography seems to confirm what many sociologists claim is the "ghettoisation" of some suburbs, which seem to swallow up even the brightest and best. The fear is that it may be precisely these young people who become the most disenchanted and graduate from theft to crime "with a cause".
An additional worry is that the identification of these suburbs and this section of the population with terrorism could open a permanent rift between the diverse communities in France. Mr Chirac in his interview on Sunday night was as careful as his ministers have been to distinguish between the "vast majority of peaceable, law-abiding Muslims" and the "tiny minority" of others.
France's religious leaders yesterday issued a declaration appealing for solidarity. But the fact that they turned up in person to present the statement showed how seriously the danger of a rift is being taken.