A man on France’s terror watch list shot selfies with the decapitated body of his boss before launching an attempted suicide attack at a U.S.-owned chemical factory, a prosecutor said Tuesday at a press briefing.

Those photos made with suspect Yassin Salhi’s phone may become part of a social media propaganda campaign for ISIS, said Paris prosecutor François Molins, whose office handles anti-terrorism cases throughout France.

Authorities said they located phone messages from Salhi’s friend in Syria that confirmed receipt of two photos. The friend apparently told relatives he planned to ask the Islamist militant organization for permission to disseminate the pictures, Molins said.

Salhi will be investigated on terrorism-related charges though he told police he acted for personal reasons — conflict with his boss and tensions with his wife, Molins said.

“The beheading, the sinister staging, the willingness to provoke an explosion in a sensitive site, sending pictures as a trophy for his crime to a correspondent in Syria — all this causes a shock, which of course gravely disturbs public order through intimidation and terror,” the prosecutor said.

Security has been heightened in France since January when Islamist attackers targeted the satirical magazine Charlie Hebdo and a kosher grocery store.

Salhi was stopped Friday before he could explode gas canisters at the factory in Saint-Quentin-Fallavier, about 30 kilometers (18 miles) outside Lyon, authorities said. The severed head of Salhi’s boss was found hanging from a fence, along with two banners that bore Islamic writing.

Molins confirmed information Tuesday about the selfie that circulated in French media.

“Analysis conducted on the phone of Yassin Sahli has uncovered two photographs taken on the same day at precisely 9:33 a.m.,” he said. “The first one showed the body of the victim wrapped in flags, his head resting on the trunk, and the second a kind of selfie in which the alleged perpetrator posed with the body of the victim. Two shots he immediately sent to Syria, to a friend … via whatsApp.”

Molins said they also located messages on another phone related to Sébastien Younes, a friend of Salhi’s who has been in Syria since November. Molins said the messages showed Younes had received the two pictures and had “asked permission to the terrorist organization Islamic State to disseminate them.”

The prosecutor said Salhi’s phone contained texts showing he was unhappy with his wife’s lack of religious involvement.

Molins also said Salhi is displaying a “selective memory” and claimed he can’t remember severing the head of his boss or sending photos.

On Friday, Salhi drove to the transport company where he worked carrying a knife with a 20-centimeter (7.9-inch) blade, a fake pump-action shotgun he repainted the day before and two flags with Muslim professions of faith that he purchased the day before, Molins said.

Salhi lured his boss, Herve Cornora, into the minivan, knocked him out with a tire jack and strangled him, Molins said Salhi told investigators.

He drove the van to the factory, Air Products & Chemicals, which supplies gases for industrial use, but before arriving went into the back of the van and decapitated Cornora, Molins said. The prosecutor said it’s not clear if Cornora was dead or alive at the time.

The vehicle was allowed through the gates because the van had been used to make previous deliveries and Salhi was recognized as a transport company employee.

About seven minutes later, Salhi’s van appears on security cameras accelerating toward a warehouse containing canisters of gas, acetone and liquid air, Molins said Monday at a press briefing. Then there was an explosion so loud residents two miles away could hear it. The blast damaged the warehouse and destroyed the roof and back of the vehicle.

When firefighters arrived about five minutes after the explosion, they say they found Salhi trying to open canisters of acetone. An explosion could have killed Salhi as well as the 75 people working at the factory, Molins said.

While examining damage to the warehouse, officials found Cornora’s head tied to the factory’s fence, along with two flags bearing “the Islamist profession of faith,” authorities said.

“We can note that this pPolice and firefighters gather at the entrance of Air Products & Chemicals, a gas factory near Lyon, France, on Friday, June 26, after a terror attack. One person has been beheaded and two people injured, French President François Hollande said Friday. A suspect has been arrested, he said.erfectly matches ISIS’ watchword, which regularly calls for committing terrorist attacks on the French territory, and to precisely slit the throats of the nonbelievers,” Molins said. “The beheading also precisely recalls this terrorist organization’s modus operandi.”

Authorities say Salhi has been married for 10 years and has three children. Salhi’s wife and sister were taken into custody, along with another person, according to Molins. They are being investigated for involvement in a terrorist conspiracy.

Salhi had been on the terrorist watch list since 2006.

In 2003, intelligence services noticed his ties to a militant group in Pontarlier in eastern France, and he often saw a radical figure called “Great Ali” from 2003 to 2005, Molins said.

In 2003 and 2004, Salhi went several times to Morocco and Saudi Arabia, prosecutors said, and he may have spent a year in Syria with his wife and children in 2009.

In 2011, he appeared to be maintaining ties with an individual with links to the suspected terrorist organization Forsane Alizza, Molins said, and a neighbor had reported last spring that Salhi was holding religious meetings at his home.

A memorial for Cornora, 54, was held Saturday in his hometown, Fontaines-sur-Saône, more than 11 kilometers (about 7 miles) north of Lyon. Residents of his neighborhood gathered to listen to the town’s mayor eulogize Cornora, who was a personal friend.

Mayor Thierry Pouzol said Cornora was deeply connected to his community and tried to help his neighbors. He “took care of others,” Pouzol said during the emotional tribute broadcast on French TV. “Today, we are all with Herve,” he said, asking the people gathered to “maintain reserve and dignity to honor (Cornora’s) memory.”

As reported by CNN