Lakdim had already shot dead the supermarket's butcher and a customer when Beltrame offered to take the place of a woman he had taken hostage.
A gun-wielding extremist went on a rampage Friday in a quiet corner of southern France, killing three people as he hijacked a vehicle, opened fire on police and took hostages in a supermarket, where panicked shoppers hid in a meat locker or ran through the aisles.
He was shot dead by police after killing and injuring a number of people in separate incidents, including taking hostages at a supermarket in the town of Trèbes.
Known for his courage and sang-froid, Lt. Col. Arnaud Beltrame was acclaimed by neighbors, colleagues and French authorities as a hero Saturday after his death from wounds the day before.
Of around 50 people in the store at the time, most were able to get out through an emergency exit, some after sheltering in a meat refrigerator.
A 17-year-old man described as a friend of Lakdim's who was under his sway, is also in custody over the attack.More news: Stock's Average True Range to Track - Flex Ltd. (NASDAQ:FLEX)
Interior Minister Gerard Collomb praised Beltrame as a hero.
The IS militant group on Friday claimed responsibility for the attack. Molins said that several explosive devices were placed around the supermarket by Lakdim and the attacker threatened to set them off.
Police killed the gunman after he had shot and stabbed Beltrame, who died of his injuries early on Saturday (March 24).
Investigators found notes at Lakdim's home which referred to IS, a legal source said, including a hand-written letter in which he claimed allegiance to the jihadi group.
"He had been on a watch list for his radicalization and links to the Salafist movement", said top anti-terror prosecutor Francois Molins.
The pope said that "I condemn such acts of indiscriminate violence which cause so much suffering, and fervently ask God for the gift of peace".More news: New York Giants sign former Miami Dolphins safety Michael Thomas
During a standoff with police he demanded the release of Paris attacker Salah Abdeslam.
The terrorist attacks which happened Friday in France has caused totaly five deaths, including Beltrame, three other civil people, and the terrorist himself.
"We are part of France, we are French ... so we have to, during very hard times like these, we have to be there", he said.
Paris - The mother of a French policeman killed in an attack last week after he swapped himself for a hostage said on Monday she was proud of his actions, and did not feel hate toward his killer.
She added that she feels no hatred towards her son's killer, only "indifference and the greatest sense of contempt", and said people should "show the photos of heroes, not killers and monsters", The Local reported.More news: Russian shopping mall inferno toll 64