PARIS (Reuters) - French police have re-opened an internal investigation into the suspected Islamist sympathies of a senior police officer, three sources close to the police said, as part of a security review after a police IT worker killed four colleagues in a knife rampage.

FILE PHOTO: French police secure the area in front of the Paris Police headquarters in Paris, France, October 3, 2019. REUTERS/Philippe Wojazer

Colleagues of Mickael Harpon, a convert to Islam, had alerted bosses four years ago that they were concerned that he was behaving unusually, but no formal investigation was launched and he kept his job.

Harpon was shot dead by police after fatally stabbing four co-workers with a kitchen knife on Oct. 3 at the Paris police headquarters. French Interior Minister Cristophe Castaner is facing calls from opposition politicians to quit over missed opportunities to spot Harpon’s radicalisation.

The lapse has prompted the far-reaching review, as well as soul-searching inside the French state about how to stop Islamists infiltrating the security services.

Five police sources who spoke to Reuters said there has been a culture of reticence inside the police about reporting colleagues’ possible radicalisation to superiors, driven in part by concerns about appearing racist or anti-Muslim.

Rights groups worry about Muslims being unduly scrutinized.

Michel Tubiana, honorary president of France’s Human Rights League, said that as Muslims’ religious practices are often visible, such as praying at the office or observing Ramadan, they could mistakenly be taken as a sign of radicalisation.

“We should be cautious not to stigmatize a whole (Muslim) community just because its members are more religious than most people in France,” he said.

The issue goes to the heart of how European countries can have security forces that reflect society by including Muslims and other minorities, but also be able to root out radicalised individuals from within their own ranks.

CASE RE-OPENED

According to two of the three sources close to the police who spoke to Reuters about the investigation into the senior officer, police chiefs are preparing to suspend him as a precautionary measure. One of the three sources, and another police source, said his service weapon had been taken from him.

The sources said the officer works in a leadership role in a unit that has access to a highly sensitive listing of people with links to terrorism.

Several years ago after he converted to Islam, the officer embraced conservative religious practices which -- while in their own right did not show any militant sympathies -- were enough of a concern to prompt an investigation, according to the three sources.

The investigation took place in 2011, one of the sources said. It resulted in no action because it concluded there was no proof of radicalisation. Since then, the officer did nothing specific to raise alarm, one of the sources said.

However, the Oct. 3 knife attack prompted a decision to re-examine the case, the three sources said.

“The chief of police could not leave this case closed”, said one of the three sources.

A spokesman from the Paris police headquarters declined to comment.

RELUCTANCE TO REPORT

In the case of Harpon, an internal report released by the French authorities said that in 2015 two of Harpon’s co-workers complained about his behavior.

The IT technician, who lived with his wife and two children in a working-class suburb of Paris with a large Muslim community, was originally from the French Caribbean island of Martinique. He was hard of hearing.

After Islamist gunmen killed 12 staff at French satirical magazine Charlie Hebdo in January 2015, Harpon expressed disdain for the victims. His co-workers, on hearing that, made a verbal report to bosses, according to the internal report.

But the co-workers declined to submit a written complaint, and the complaint never went beyond the boss of Harpon’s department. He concluded that Harpon posed no threat, according to the authorities.

Officials with police trade unions, lawmakers, and police sources said while they could not comment specifically on Harpon’s case, the police rank-and-file’s reluctance to report on colleagues stemmed from several factors.

Those included the lack of a legal definition of radicalisation, the blurred line between religious devotion and radicalism, and an unwillingness to break ranks in a police force steeped in ideas of teamwork and trust.

According to five sources close to the police, one factor stopping people from reporting colleagues was a worry about being branded racist or anti-Muslim.

Eric Poulliat, a lawmaker with President Emmanuel Macron’s LaRem party, said he found that concern was a common thread when he was researching a report, published this year, on radicalisation in French public services.

The solution, he said, was to ignore the religious or ethnic affiliation of the person involved. “A colleague should be treated like everyone else and if he crosses a red line, he crossed it, and that should be flagged up,” said Poulliat.