French police on Wednesday arrested a 22-year-old man in connection with the stabbing on Saturday of a French soldier in a Paris suburb, with officials describing the suspect as a fairly recent convert to Islam…

Officials said at the time that the attack seemed an echo of the killing and stabbing to death of a British soldier on a London street last week.

The French suspect was known to investigators, Mr. Valls said, but he urged caution and said: “I cannot talk about radical Islam.” He said investigators wanted to know more about the suspect’s “motivation, background and family environment.”