People visit the makeshift memorial at the Saint-Étienne-du-Rouvray church where priest Jacques Hamel was killed during an attack claimed by the Islamic State. (Charly Triballeau/AFP via Getty Images)

Both attackers who stormed a French church and killed an elderly priest had been on watch lists, authorities said Thursday as new details emerged about the assailants’ apparent attempts to reach Islamic State territory in Syria.

The latest revelations about Tuesday’s attack are likely to add pressure on authorities over their protocol for monitoring suspected militants, as well as increase calls to boost intelligence services amid a greater shift to focusing on potential homegrown radicals rather than those returning from abroad.

French officials identified the second church assailant as Abdel Malik Nabil Petitjean, 19, a French native of the eastern region of Vosges.

Petitjean was also known to French authorities since June 29 as a potential Islamist militant, police sources told the Reuters news agency without giving details of the probes.

The other attacker, Adel Kermiche, also 19, had been required to wear an electronic ankle bracelet that allowed authorities to trace his movements.

Both had attempted to enter Syria from Turkey but were turned away, officials said.

Petitjean and Kermiche swept into the church in Saint-Étienne-du-Rouvray, a suburb of Rouen in the northern Normandy region, and slit the throat of Jacques Hamel, a beloved 85-year-old priest. The two attackers were later shot dead by police.

The two also reportedly wounded an elderly man, who authorities say is no longer in life-threatening condition.

On Tuesday, Kermiche and Petitjean were shown in a video, released by the Islamic State, pledging allegiance to the group’s self-proclaimed caliphate.

In Turkey, a senior official said Thursday that Kermiche, using the alias Kevin Kermiche, was stopped by airport authorities in Istanbul and sent back to Geneva on May 14, 2015. France was immediately informed about Kermiche’s deportation, said the official, who spoke on condition of anonymity under government protocol.

Two attackers stormed a village church during Mass in northern France Tuesday. The pair took hostages and slit the throat of an 85-year-old priest. (James McAuley and Jason Aldag / The Washington Post)

Kermiche was imprisoned, but he was released in March, placed under monitoring and required to meet weekly with a probation officer.

As more details emerge in the investigation, many critics have questioned how a suspect such as Kermiche was allowed to roam the streets. Kermiche was allowed to leave his parents' house — located in Rouen near the village church — for four hours every weekday.

"He was actually following the rules," said François Heisbourg, a former member of a French presidential commission on national security and defense, in an interview. "These are some of the things that we really have to do something about."

Kermiche’s case has also focused attention on possible staffing shortfalls in France's Ministry of Justice, which includes the probation department.

Pascale Loué-Williaume, the national secretary of the Union of Magistrates, France's largest union of judges, said many probation officers, police and gendarmes were cut in cost-saving moves during the presidency of Nicolas Sarkozy.

The former president, harshly critical of the current French government's anti-terrorist measures in the wake of a deadly attack this month in Nice, has since come under fire for gutting security forces during his tenure.

Diminished numbers, Loué-Williaume said, create "an enormous amount of work" for the probation officers who are in place.

"We need more people to monitor properly all the people convicted. We need more to contribute — more to surveil in the prisons and more to follow them later."

Ishaan Tharoor in Istanbul contributed to this report.