(Reuters) - Tasneem Hussein was a soft-spoken university student in Khartoum when the transformation slowly began.
After returning to Sudan from Britain to study pharmacology, she swapped her jeans for the head-to-toe niqab covering. But no one expected to hear reports of her abandoning her studies and a privileged life to help Islamic State wage jihad in http://www.reuters.com/places/syriaSyria.
Last week, the 23-year-old told her parents she would be spending the night with relatives.
The next day she sent a Whatsapp message saying she was studying for a Masters exam at the university library, according to a person close to the family, who declined to be named due to the sensitivities of the matter.
In fact, Hussein went to Turkey with a group of other British-Sudanese medical students en route to Syria, ostensibly to back Islamic State.
To many people, the group that now controls large areas of Iraq and Syria is notorious for beheading Western captives and burning a Jordanian military pilot alive. It imposes strict Islamist rule in its fiefdoms, including repressing women. But for some youngsters like Hussein, it may have had an appeal.
She used to "join us in parties and occasions with neighbours. She use to wear jeans and then two years ago a big change happened and she started wearing the niqab," said the neighbour, who saw Hussein the day she left for Turkey and did not detect anything unusual.
Unlike Britons indoctrinated by militant ideology in mosques in the United Kingdom, Hussein and her comrades were introduced to fundamentalist thought at religious lectures in their university.
Their journey to Syria illustrates the complex challenges Western and Arab states face in trying to contain the appeal of Islamic State, which has succeeded in attracting young European-born Muslims to their ideal of a medieval caliphate.
This group, which included both medical students and new graduates, are worlds apart from the stereotypical profile of many militants - poor, disaffected, angry, youths.
Most of them come from well-to-do families who have no connection to extremist circles in Khartoum.
Hussein's father is well-known in Sudanese society and is the head of one of Sudan's largest government hospitals.
Neighbours say the family lives in the elite Riyadh district in a three-storey villa with a large garden on a tree-lined street where several luxury cars are often parked in the driveway.
"Before her transformation, Tasneem was an open, moderately conservative girl like the rest of her family," said the person who is close to the family.
When she wore the niqab, her parents apparently questioned her decision, but failed to realise she was on a dangerous path.
Sudan, which hosted al Qaeda founder Osama bin Laden in the 1990s, promotes a conservative brand of Sunni Islam which may appease hardline groups.
Long-ruling President Omar Hassan al-Bashir, who came to power in a 1989 coup, introduced sharia law, creating an official tolerance to Islamism.
The University of Medical Sciences and Technology (UMST), where the group studied, was founded by Khartoum governorate Health Minister Ma'amoun Houmeyda, a known Islamist.
A walk across campus showed most students wearing Western attire, unusual in the conservative country. But UMST has also hosted firebrand clerics like Sheikh Mohammed al-Jizouli who has given sermons supporting Islamic State and called on people to "leave the bleachers and go to seats of martyrdom".
Jizouli was arrested a few months ago and it was not immediately possible to verify whether anyone in the group had listened to his sermons, but it is likely.
Ahmed Babaker, UMST's dean of students, said the group got together in an apartment in an upscale area of Khartoum and that it was recruited by Mohammed Fakhri -- a Briton of Palestinian origin -- who left for Britain after graduating from UMST and from there went toSyria and joined Islamic State.
The neighbours and friends Reuters spoke to all seemed to lay at least some of the blame on the Islamic Civilisation student organisation which brought clerics like Jizouli to deliver sermons calling for jihad.
"After two students travelled to Mali to join religious groups, we halted the activities of the clerics," Babaker said.
While the university was not shutting down the group, it said it was starting awareness programmes.
"After the escape of this group, there's cooperation with security and intelligence services to monitor suspicious students. We in the university are very worried about his phenomenon and we're trying to stop it form happening again."
It may be too late. The clerics had a deep influence on the students.
"In the beginning I did not wear the hijab or the niqab and the lectures by the Islamic Civilisation organisation used to teach us how to pray well," said a female student who spoke to Reuters, wearing the niqab face covering.
"That was in the first stage, in the second stage the conversation was about the oppression facing Muslims in Palestine and Syria and the necessity of Jihad."
Britain's security services estimate that about 600 Britons have gone to Syria or http://www.reuters.com/places/iraqIraq to join militant groups, including the man known as "Jihadi John", who has appeared in several Islamic State beheading videos.
Islamic State's attempt to create a theocratic Sunni Muslim 'caliphate' by violent means has attracted thousands of recruits from Europe and elsewhere.
"The government is extremely disturbed about reports that this group of young people left to join Daesh because the normal situation is for these students to be in university halls, said Sudanese investment minister Mostafa Othman Ismaeil, using a derogatory Arabic term for Islamic State.
"And it's the government's duty to bring the group home."
It is not clear how the Sudanese government will do that, or prevent other students from supporting Islamic State.
Jihadist movements have been on the rise in Sudan and across the region since the 2011 Arab Spring uprisings which toppled autocrats and unleashed militant groups they suppressed.
In Sudan, they emerged on university campuses, unchecked by the Islamist-led government.
"The activities of these groups is growing and they carry out recruitment operations," said Sudanese analyst AlHadi Mohammed al-Amin.
"Sudanese youths go and fight in Somalia, Mali, http://www.reuters.com/places/libyaLibya, Syria and Iraq. This phenomenon is on the increase and the Sudanese government is not too concerned with fundamentalism because they do not represent a danger to the government itself."
The government, Amin said, was preoccupied with the several wars it is fighting with various rebel groups in the country.
Several parents of the students have gone to the Turkey-Syria border to try and find their sons and daughters.
Some students who knew the group said they could not believe they had actually joined Islamic State.
"Some of them told their parents over Whatsapp after they left Sudan that they would not get embroiled in jihad with Daesh but that they had gone to provide medical services for the mujahideen," students who knew some members of the group said.
A Turkish member of parliament said last week that the group were to have travelled toSyria to work in hospitals controlled by Islamic State.
Families of the students expressed disbelief that they had joined the militant group.
"We believe that they have arrived in Turkey, but they have disappeared and we do not know their whereabouts. We, the parents would like to announce that our children have good intentions," they said in a statement.
(Writing by Yara Bayoumy; Editing by Michael Georgy and http://blogs.reuters.com/search/journalist.php?edition=us&" style="color: rgb(0, 110, 151); text-decoration: none; background: transparent;">Angus MacSwan)