American teachers in Abu Dhabi were warned that jihadis were threatening to kill them just weeks before a 47-year-old was stabbed to death in a mall by a burqa-wearing murderer, it emerged today.

Every American in the United Arab Emirates was warned today step up their security today after the kindergarten teacher was stabbed to death by a knife-wielding murderer in a burqa.

Ibolya Ryan, a mother of twin 11-year-old boys, was left dying in a pool of blood by the murderer after what police said was a 'brawl' in the toilets of a mall.

Detectives today released CCTV footage which showed how the suspect - whose gender they say they have not confirmed - lay in wait for the teacher for an hour.

It suggests strongly the attack was a targeted murder. Witnesses today told MailOnline the victim had been stabbed up to six times.

The victim was named by CNN as Ibolya Ryan, 47, a US-trained teacher who was described in an online profile as Hungarian-born and raised in Romania. She trained as a teacher in the United States.

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Mom: Ibolya Ryan, 47, named as the victim by CNN, was the mother of 11-year-old twin boys. She was previously married to Paul Ryan, and the couple had lived in Denver, Colorado

Professional: Ibolya Ryan, 47, in the picture she used on social networking profiles

Victim; Ibolya Ryan was named by CNN as the victim. She describes herself online as a Hungarian who was born and raised in Romania but trained as a teacher in the USA.

On way: The suspect enters the mall at 1.13pm local time and is captured as they come in from the car park

Waiting: The suspect waits briefly for the elevator to the main mall level of the shopping complex

Asking directions? The suspect approaches a security guard after getting out of the elevator

The burqa-clad suspect lifts a free newspaper before heading into the toilets of the mall

Victim: Ibolya Ryan was named as the dead woman. She previously lived in Denver, Colorado, with her ex-husband Paul Ryan, 48

The 47-year-old murder victim, the mother of twin 11-year-old boys, was left in a pool of blood in the toilets of the upmarket Bourik Mall.

As security guards rushed to the scene of the killing, her attacker calmly got in an elevator and walked out into the car park.

The assailant - who police believe could be a man wearing a burqa - left behind the weapon, a large kitchen knife.

The victim - who is divorced from the father of the twins - described herself in an online profile as a teacher at a large kindergarten called Al Oula in Abu Dhabi, 35 minutes away from the downtown area of the emirate.

She wrote: 'I enjoy learning about other cultures, and as a person I enjoy being with others and tend to be an organizer of those around me.

'Also I have high interest in other languages; one of my goals while here in the UAE is to gain some proficiency in Arabic.

'I live in Abu Dhabi with my 10-year-old twin boys and I teach in a big KG school named Al Oula KG School, 35 minutes away from downtown Abu Dhabi.'

Officers are still trying to determine the reasons for the attack and the identity of the suspect, who fled the scene wearing an abaya, black gloves and the face-covering veil known as a niqab.

The victim's ex-husband was said to be overseas but was flying back to comfort his sons, who are 11. Police had reported her age initially as 37.

Mrs Ryan, whose maiden name is Balaszi, had previously lived in Denver, Colorado, where she worked as a special educational needs teacher and took a course in teaching English as a foreign language.

She has also worked as an executive assistant at a Colorado technology company, an event planner at a Hungarian hotel, a substitute teacher at the American International School in Vienna, and a part-time events planner in Abu Dhabi.

Mrs Ryan lived in a beachside apartment on Reem Island, where the mall where she was murdered is situated. Her ex-husband, Paul, 48, is believed to currently live in Europe.

Today America's embassy in Abu Dhabi, the capital of the United Arab Emirates, issued new security advice to US citizens.

In a statement, the embassy said: 'On December 1, a U.S. citizen was killed in a public restroom at a shopping mall on Reem Island in Abu Dhabi. The U.S. Embassy is working with all the appropriate authorities to seek further information.'

It listed extra precautions for US citizens, saying they should avoid crowds and places they did not know previously, and 'minimize their profile in public'.

Warning: What teachers in Abu Dhabi were told a month ago by the US Embassy to the United Arab Emirates. It said jihadi websites wanted American teachers to be attacked.

Horror: The murder weapon was found near the woman's body where it had been abandoned by her killer

Find: The CCTV footage shows how the knife was found directly under a door in the toilets

Trail of blood: The crime scene was covered in the victim's blood in images revealed by police in Abu Dhabi

Frenzy: The scene of crime shows the bloody horror in which the American mom died

Forensic investigation: The aftermath of the attack as police investigate what happened in the toilets

The embassy did not say it was linked the murder to the jihadi threat.

That was highlighted to US citizens at the end of October in a statement on the embassy website.

It said: 'The Embassy/Consulate wishes to notify the U.S. citizen community of a recent anonymous posting on a Jihadist website that encouraged attacks against teachers at American and other international schools in the Middle East.

'The Mission is unaware of any specific, credible threat against any American or other school or individual in the United Arab Emirates (UAE).

'Nonetheless, the Mission is working with local schools identified with the United States to review their security posture. U.S. citizens residing in or visiting the UAE should remain vigilant regarding their personal security and be alert to local security developments.'

The CCTV footage establishes that the woman spent at least an hour apparently waiting in the toilets of the mall.

She entered the mall from the car park at 1.12pm, and a minute later was on the mall level where she got out of the elevator where she approached a security guard.

After apparently asking for directions - there is no audio footage - she moved towards the restrooms, picking up a free newspaper on the way.

An hour and a half later she left the toilets - at precisely the time people are scene reacting to the horror.

After the crime: As people appear to be alerted to something happening in the toilets and a woman with a child rushes from them while a security guard moves along the corridor into them, the suspect moves towards the elevators

Calm departure: The suspect is standing directly between the elevators after almost colliding with another woman to her left, who is wearing a white top. Onlookers (right) are reacting in horror to the discovery

Attempt to stop?: A man apparently tries to stop the elevator the woman has just taken from going as security guards run towards it

Last seen: The burqa-clad suspect's last sighting on CCTV as 'she' moves quickly out of the mall

One mother with a young child can be seen hurrying him away while security guards move towards the corridor.

At the same time the suspect bumps into another woman before being directed towards the elevator.

Then she calmly goes down to the parking garage and is last seen moving towards cars in it.

But at the same time security guards come out of the toilets and apparently try to stop the elevator from leaving - too late to stop the murderer's calm departure.

The suspect is last seen exiting left from the mall's parking garage entrance.

Witnesses told MailOnline today that they overheard a heated row between two women - then heard one threaten to kill the other.

Vithi Cuc, a Vietnamese restaurant worker, was in a toilet cubicle when she heard banging sounds from the disabled toilet cubicle next door.

She said:'Then I heard one of them threatening the other saying: 'Sit down or I'll kill you.'

'I heard one of them try to call out for help. By this time there were three of us outside the toilet and one of us ran to get security.

'When the female guard arrived they told us to leave the bathroom. I was so scared and frightened for her.'

Another witness said he saw a woman bleeding on the floor outside the entrance to Waitrose, the upscale British supermarket nearest the toilets in the mall.

Bernadette Ruizo, manager of La Brioche restaurant near the scene of the murder, said: 'I heard she was stabbed five or six times.

'None of us knows exactly what happened as it was so busy in the restaurant.

SECURITY ADVICE TO US CITIZENS Avoid large crowds or gatherings of unknown origin or circumstances when traveling in public; Know where you are going and have a plan of what to do in the event you encounter demonstrations or violence; Identify safe areas (for example police stations, hospitals) in your area and how to get to them quickly; Tell co-workers or neighbors where you're going and when you intend to return;Minimize your profile while in public; Always carry a cell phone and make sure you have emergency numbers pre-programmed into your phone such as the U.S. Embassy in Abu Dhabi and U.S. Consulate General in Dubai; Be prepared to postpone or cancel activities for personal safety concerns. Source: US Embassy in Abu Dhabi Advertisement

'There was a crowd around the toilet entrance and I only found out afterwards what had happened.'

Today a cordon and screen had been erected at the entrance to the corridor leading to the toilets.

Colonel Rashid Bourshid, director of the criminal investigation department of Abu Dhabi police, said: 'Police found the woman lying on the floor bleeding.

'She had serious wounds after being stabbed with a knife during a brawl with the attacker.

'No reason has been established yet as to why the woman was murdered. The attacker fled the scene after stabbing the woman.'

Col Bourshid said a murder investigation had been launched and police were searching for the suspect.

He added: 'Community policing is now taking care of the two boys and will provide them with shelter and all necessary support until their father, who stays outside the UAE, arrives.'

A friend of the dead woman told MailOnline she was a devoted mother.

Sandra Fu, a manager at the GCC Business Council which Mrs Ryan helped organise events for, said she often showed colleagues pictures of her children.

She said: 'She was very outgoing and a very good mother. She was trying to support her family and her children all the time and I believe it was hard.

'She was helping us do some events in Abu Dhabi because her profession involves organising events.

'She worked very hard to support her family. I never met her children, I have only seen photos.

'We had not met for a couple of months. She told us she could not continue organising events for us because she had a full-time job.

Reem Island is a residential, commercial and business development connected to Abu Dhabi city centre by a bridge. It was built as the city center became over-populated.

It is mostly inhabited by expatriates and boasts the upmarket Boutik Mall, which opened in 2011 and has 50 shops and restaurants, including the capital city's first Waitrose, the upscale British supermarket chain, Leopold's of London and La Brioche.

Scene: The crime scene today. The elevator in the center of the picture is how the suspect fled, and the advertising hoarding is in front of the entrance to the mall toilets where the murder took place

New: The mall where the attack took place opened in 2011 and has 50 shops and restaurants. It caters for a mix of expatriates and wealthy locals

The mall bridges two residential buildings, Sun and Sky towers. Its website says it 'offers the best of everything that anyone needs to lead a stylish life.

'Serving the vibrant and cosmopolitan community of Shams Abu Dhabi and beyond, Boutik is an oasis of independent retailers, brand outlets, comfortable cafes and day-to-day services.

'For busy professionals living and working in the adjoining towers and for students at the Sorbonne, it is a welcome social centre and cornerstone of the community.'

Although Abu Dhabi is not the largest emirate - Dubai has the biggest population - it has an estimated 40,000 American expatriates.