In policy debates, the detrimental effects of migration on crime, particularly gang crime, do not receive nearly the attention -- if any -- they deserve. They should.

"In addition to a common fondness for crime, the culture of immigrant gangs is a cocktail of religion, clan affiliation, honor, shame and brotherhood... The harder and the more brutal [you are], the stronger you are, and then you create awareness of yourself and attract more [people]". — Naser Khader, member of the Danish Parliament for the Conservative Party and co-founder of the Muslim Reform Movement, Jyllands-Posten , November 22, 2018.

"...traffickers tell victims of human trafficking to apply for asylum and then get a status to be able to stay here in Germany, but they continue to be exploited in prostitution." — Andrea Tivig, Terre des Femmes , Infomigrants.net, March 15, 2019.

Black Axe has also spread to Canada, where a 2015 report by the Globe and Mail described it as a "death cult"... linked to "decades of murders and rapes.... In the US, the FBI recently linked a series of financial frauds to Black Axe.

Italian intelligence has named the Nigerian mafia "the most structured and dynamic" of any foreign crime entity operating in Italy, according to the Washington Post .... What distinguishes the Nigerian crime networks is their severe brutality...

It is no wonder that the Nigerian mafia has become so prominent in Italy: the country has been one of Europe's front doors for migrants entering Europe. Pictured: An inflatable boat attempting to cross the Mediterranean Sea to Italy with 47 African migrants on board, as it is being rescued by the Dutch-flagged Sea Watch 3 off Libya's coast on January 19, 2019. (Photo by Federico Scoppa/AFP via Getty Images)

One of the fastest growing criminal networks in Europe is now the Nigerian mafia, which is spreading its criminal activities across the continent. It consists of rival groups such as Black Axe, Vikings and Maphite. Most recently, authorities in Italy, France, Germany, the Netherlands and Malta conducted an international operation directed at two of the major Nigerian mafia groups. Police accused the gangs of human-trafficking, drug trafficking, robbery, extortion, sexual violence and prostitution.

According to a June 2019 report by the Washington Post on the Nigerian mafia in Italy:

"They hold territory from the north in Turin to the south in Palermo. They smuggle drugs and traffic women, deploying them as prostitutes on Italy's streets. They find new members among the caste of wayward migrants, illicitly recruiting at Italian government-run asylum centers."

The Nigerian mafia, according to the report, is "trafficking women by the tens of thousands". Italian intelligence has named the group "the most structured and dynamic" of any foreign crime entity operating in Italy, according to the Washington Post.

"Some experts say that as many as 20,000 Nigerian women, some of them minors, arrived in Sicily between 2016 and 2018, trafficked in cooperation with Nigerians in Italy and back home."

It is no wonder that the Nigerian group has become so prominent in Italy: the country has been one of Europe's front doors for migrants entering Europe.

What distinguishes the Nigerian crime networks is their severe brutality -- Italian police have described them as using "urban guerilla warfare" to hold on to territory in Italy -- and their use of voodoo rituals. According to a July 2017 report by the UN's International Organization for Migration (IOM), sex trafficked victims give an oath "sealed with a voodoo ritual or a rite of initiation (the victim is committed to honouring her agreement)" to their traffickers and also harbor "a fear of retaliation by traffickers on the victim's family members back in their country of origin".

According to the 2017 IOM report:

"Over the past three years, IOM Italy has seen an almost 600 per cent increase in the number of potential sex trafficking victims arriving in Italy by sea. This upward trend has continued during the first six months of 2017, with most victims arriving from Nigeria".

In its report, IOM estimated that 80 per cent of girls, often minors, arriving from Nigeria -- whose numbers soared dramatically from 1,454 in 2014 to 11,009 in 2016 -- were "potential victims of trafficking for sexual exploitation".

The Nigerian mafia has not limited its operations to just Italy. It has spread as far north in Europe as Germany and Sweden. In London, a trio of Black Axe members was found guilty of laundering almost £1 million, which had been stolen through phone and email fraud. The Nigerian mafia, specifically the group Black Axe, has also spread to Canada, where a 2015 report by the Globe and Mail described it as a "death cult" originating in Nigeria, where it has been linked to "decades of murders and rapes, and its members are said to swear a blood oath". In the US, the FBI recently linked a series of financial frauds to Black Axe. According to the news report, "In the United States and around the world, the group is responsible for the loss of millions of dollars through a variety of elaborate cons".

In Sweden, police has described Black Axe as "one of the world's most effective crime syndicates". Swedish media recently ran a story that shows how Black Axe operates: A 16-year-old Nigerian girl was promised a job in Sweden as a hair stylist. When she arrived, Black Axe forced her to work as a prostitute, after she had gone through a voodoo ritual. "We have your blood now", Black Axe members told her, "If you run we will always find you".

In 2018, three Nigerians were prosecuted in Malmö for luring Nigerian women to Sweden with the promise of jobs and then forcing them into prostitution after making them go through a voodoo ritual that involved the eating of a raw chicken heart. According to the Swedish prosecutor, the voodoo ritual is a way to control and exploit the trafficked victims, who believe in voodoo.

Similar rituals went on in the UK in 2018, when a trafficker sought to traffic Nigerian women from Nigeria to Germany and in Spain, also in 2018, when a trafficking ring of 12 Nigerians was arrested, also for forcing women into prostitution and putting them through similar voodoo rites. In Germany, according to a recent report by Deutsche Welle, a growing number of Nigerian women are ending up as prostitutes in one of Germany's largest red-light districts in Duisburg, and according to Barbara Wellner of Solidarity with Women in Distress, "Nigerian human traffickers are responsible for smuggling in most of them".

The number of Nigerian women trafficked into prostitution in Germany, while still relatively small, has been growing in recent years, according to a March 2019 report by Info-Migrants. In 2013, just 2.8% of known victims were from Nigeria. That went up to 5% in 2016 and up to 8% in 2017. According to the report, which quotes Andrea Tivig from the women's rights organization, Terre des Femmes, the traffickers use the asylum system:

"I've heard reports in Italy... that traffickers tell victims of human trafficking to apply for asylum and then get a status to be able to stay here in Germany, but they continue to be exploited in prostitution."

The Nigerian mafia groups form just one part, albeit very troubling, of the total picture of imported migrant gang crime in Europe. As previously reported by Gatestone Institute, migrant gang crime already poses a threat to European citizens. In November 2018, Naser Khader, member of the Danish Parliament for the Conservative Party and co-founder of the Muslim Reform Movement, wrote in the Danish newspaper Jyllands-Posten:

"In addition to a common fondness for crime, the culture of immigrant gangs is a cocktail of religion, clan affiliation, honor, shame and brotherhood... The harder and the more brutal [you are], the stronger you are, and then you create awareness of yourself and attract more [people]".

In Sweden, migrant gang crime has become an almost insurmountable problem: some commentators there have described the situation as "war". Denmark is increasingly fighting migrant gang crime. In Germany, where the migrant gangs are known as criminal family clans, authorities expect to be fighting the problem for decades to come.

In policy debates, the detrimental effects of migration on crime, particularly gang crime, do not receive nearly the attention -- if any -- they deserve. They should.