At least six security force members have been killed during that period.
Paying tribute to the officer at a national ceremony in Paris on Wednesday, President Emmanuel Macron said his act of supreme self- sacrifice would "remain etched in French hearts".
After a stand-off lasting several hours, Lakdim shot Beltrame.
His 18-year-old girlfriend, a radicalised Muslim convert, was charged with being part of a terrorist conspiracy. Police immediately stormed the supermarket and killed the gunman.