Her brother, Ian, said he was 'in shock' and questioned the 'very odd circumstances' of his sister's death

United Nations colleague: 'Very difficult to believe she committed suicide'

Iraq expert: Jacky Sutton is said to have been born in Hertfordshire but more recently lived in London

A former BBC journalist found hanged in a toilet cubicle at a Turkish airport had mourned the deaths of three colleagues in terror attacks in just a month and attended a memorial to one of them days before her death, it emerged today.

Jacky Sutton, an international development worker, was found dead at Istanbul's Ataturk Airport after missing a connecting flight to Erbil in Iraq.

She appeared distressed after being told by airline staff that she would have to buy a new ticket and was later found in the toilets by three Russian passengers, according to local media.

At the end of April, Ms Sutton posted on her Facebook page the story of Sabeen Mahmud, a human rights campaigner who was killed by a gunman in Karachi, Pakistan.

Just weeks later, her predecessor at the Institute for War and Peace Reporting (IWPR), Ammar Al Shahbander, was killed in an Islamic State bomb blast in Baghdad on May 2.

On May 12, another friend, this time Paula Kantor, a researcher, was one of 15 people killed when three gunmen opened fire on a group of Westerners at the Park Palace Hotel, in Kabul.

Ms Sutton posted about the attack before she knew of her friend's involvement, calling it 'another senseless act of slaughter'.

Poignantly she wrote: 'Hoping everyone staying there gets out OK.'

She later attended a memorial service to Mr Shahbander at St Bride's Church, Fleet Street, in London just days before she was found dead.

On her Facebook page when he died, Ms Sutton paid tribute to him, writing: 'In one of the stars you shall be living.

'In one of them you shall be laughing. And so it will be as if all the stars were laughing, when I look at the sky at night. Goodnight my dear friend, Ammar Al Shahbander.'

Ms Sutton, 50, had been working in the Iraqi city of Erbil as the Iraq country director for the Institute for War and Peace Reporting (IWPR).

She was appointed to the role at the end of June following Mr Shahbander's death.

The 50-year-old held various positions with humanitarian organisations around the world and the United Nations as well as working as a producer for the BBC, often in war-torn countries, and once suffered from post-traumatic stress after being arrested for alleged spying in Africa.

Jacky Sutton's brother, Ian, 59, questioned the 'odd circumstances' surrounding his sister's death.

'There do seem to be some very odd circumstances. She had too much to live for and too many people relying on her to simply quit,' he said.

He posted a tribute to his sister on social media, describing Jacky as being 'amazing in so many ways' and 'passionate about her work.'

'I know she will be missed for her honesty, compassion, intellect and humility and those are only four words that go no way in describing the loving, complex and single-minded person she was.

'Whatever happens, Jacky is gone, but I hope we all remember her compassion and the brave actions and decision she took throughout her life,' he wrote.

Jacky Sutton with Mazin Elias in Istanbul, Turkey, in the summer of 2013. The Iraqi journalist said it was 'impossible' that she committed suicide

Ms Sutton had also of her anger at the dangerous nature of ISIS, particularly the manner in which they lure women into becoming jihadi bride.

She suggested that ISIS give vulnerable women 'a sense that they will have some kind of power relationship with the men on an equal footing; that they will be honored and respected as mothers, brides, wives and sisters,' she told Rudaw

She warns that the reality of living as a woman under ISIS is completely different.

'It is a very romantic ideal that ISIS is peddling to these young women, in the same way that the cigarette manufactures used to peddle the idea of smoking as being cool. The reality of course is very, very different,' she said.

Paying tribute to Ms Sutton, friend Amanda Whitely, posted a blog today on the website Her Canberra which included an autobiographical account of the former United Nations worker's life.

In the article, which had been intended to be a video life story for the women's online magazine, Ms Sutton told how she suffered post-traumatic distress disorder in 1995 after spending five years in Eritrea which she described as a 'life-changing' experience.

I took Prozac for a month, but it had some seriously weird side effects so I stopped Jacky Sutton on suffering from PTSD after being arrested for 'spying' in Africa in 1995

She said: 'I was detained as a spy and deported and many people fled the country.

'I got (a scholarship) to do a PhD at Leeds University, but my mother had been diagnosed with breast cancer, and I think I had PTSD from the detention so I was unable to cope.

'Now there would be counseling, but back then I was given Prozac (anti-depressants) and told to soldier on. I took Prozac for a month, but it had some seriously weird side effects so I stopped.'

In a separate e-mail to Mrs Whitely in June, she spoke of her fear that she would be targeted by the Islamic State.

She wrote: 'I'm in a hotel at the moment – a low key one with hardly any guests. The accommodation that had been prepared was basically one room and a bathroom above the office with only one door in and out, and that off the street.

'So if someone came in uninvited I was trapped and, as my Kurdish friends said, "It just needs one whacko to hear in the Friday prayers that killing foreigners is jihad, and they'll come knocking at your door in a heartbeat". Erbil has grown but everyone knows where the foreigners are staying.

'If Daesh (ISIS) wants to attack, they will but it will take planning and I won't be THE target.

'If the whacko wants to get to heaven he or she will have to contend with armed guards and a choice of targets, and the same with criminal kidnappers – a growth industry in Iraq.'

At the time of her death, Ms Sutton had just flown back from the memorial of her predecessor at the Institute for War and Peace Reporting who was killed in an Islamic State car bomb attack in Baghdad five months ago

Ms Sutton had arrived in Istanbul on Turkish Airlines flight TK-1986 at about 10pm local time on Saturday night, and was then due to fly to Erbil at about midnight, but missed her flight, it was reported.

Video footage posted on Turkish news website Haberler reportedly shows her body being carried out of the airport in a black bag.

Friends and colleagues of a British journalist and international development worker who died in Istanbul have described her reported suicide as 'impossible to understand'.

At the end of April, Ms Sutton posted on her Facebook page the story of Sabeen Mahmud, (left) a human rights campaigner who was killed by a gunman in Karachi, Pakistan. Another friend of Jacky Sutton was Paula Kantor, (right) who died during a Taliban attack on a hotel in Kabul. She was a prominent expert in international development and gender issues

Sabeen Mahmud, a prominent women's rights activist was gunned down in her car by a terrorist on a motorbike in Karachi, Pakistan

Broken glass and the bloodied sandals of Sabeen Mahmud lie inside the car after the devastating shooting in April 2015

Anthony Borden, executive director of the IWPR, called for an 'open and transparent' investigation into her death.

Mr Borden said: 'All of her friends and colleagues who knew her better than me find it impossible to understand. It doesn't accord with what anything anyone knows about her.

'I'm not going to say I knew what was in her heart and mind but she had a positive nature and outlook.

'She took her new role as a really solemn commitment following the trauma of Ammar's death.'

According to reports, Ms Sutton killed herself after missing a connecting flight to Iraq and admitting she did not have enough money to pay for another ticket.

Ms Sutton speaks to Iraqi journalist Mazin Elias, who refuses to believe that she may have killed herself

Mr Borden said: 'I know a flight from Istanbul to Erbil is a couple of hundred dollars. This is not someone on her first trip away from home.

'She was a seasoned global traveller. If you miss a flight, you go off and have a drink and relax.'

Mr Borden said Ms Sutton was in 'high spirits' when they had lunch last week and that Mr Al Shahbander's memorial service had left everyone feeling 'inspired and re-committed' to the cause.

Ms Sutton's sister is travelling to Istanbul with an IWPR employee to meet with British and Turkish officials, the organisation confirmed.

Iraqi journalist Mazin Elias, who had worked with her, told MailOnline that it was 'impossible' that she committed suicide, alleging that 'someone killed Jacky'.

Mr Elias said she was dedicated to developing freedom of expression in Iraq and was also trying to better herself by studying for her PhD.

'She continued in Iraq – everything was difficult, everything was a challenge, but she still continued.

'But, what I'm sure about, the kind of person that Jacky was, it's impossible she would have killed herself, impossible.

'She's really looking for a better life for everyone. So kill herself? That's crazy.

'I'm really sad and sorry what happened, but if someone tells me 'she killed herself', I tell him: 'No, that's wrong, someone killed Jacky'.'

He also thought it extremely unlikely she would have missed her flight.

Ms Sutton's IWPR predecessor Ammar Al Shahbander who was killed in a car bomb attack in Baghdad in May

Devastating: The Islamic State claimed responsibility for the car bomb attack outside a popular Baghdad restaurant in May that killed 15 people including four policemen and Mr Shahbander

He added: 'No, that's impossible... we're not talking about a girl. She's a woman, an official woman, she's a big manager.'

Sudipto Mukerjee, a country director with the United Nations Development Programme, wrote: 'Very difficult to believe that my colleague @undpiniraq staffer and seasoned traveler @JackySutton committed suicide.'

Another friend and colleague, Christian Bleuer, also expressed his doubts on Twitter.

Ge wrote: 'Toughest woman u could meet. Turkish police say she committed suicide cuz she missed her flight?'

He added: 'I'm not into conspiracies, but if the Turks say a security camera at Istanbul-Ataturk was 'malfunctioning' then Jacky Sutton was murdered.'

Susan Hutchinson, a colleague at the Australian National University where she had been studying for a PhD, also said she did not believe it was suicide.

Travelling: The former BBC journalist had flown from London Heathrow to Istanbul's Ataturk Airport (file picture), but is believed to have failed to make it on her next flight to Erbil in Iraq

She told the ABC: 'I am unconvinced that she would have committed suicide... I am sceptical of the idea. I absolutely think that there needs to be a full investigation.

'I hope the (British) Foreign Office has full access in order to be able to conduct a proper investigation about the circumstances in which Jacky died and I hope that that is done internationally and in a transparent and cooperative way.'

She said the IWPR had recently 'taken up work countering the anti-women messaging' of the Islamic State.

Journalist and international development worker Rebecca Cooke also called for an international investigation.

She said: 'Shocking and sad news about the death of Jacky Sutton in Istanbul. An international not just local investigation is needed.'

I am unconvinced she would have committed suicide. There needs to be a full investigation Susan Hutchinson, a colleague at the Australian National University

Ms Sutton is thought to have been the acting Iraq director for the IWPR, an organisation that supports journalists and activists in conflict-hit countries.

Ms Sutton was born in Hatfield, Hertfordshire and spent her early years living in the former grounds of Hatfield House, before her family moved to Maldon, Essex when she was seven.

She was one of four children, with two sisters and a brother. Her mother died from breast cancer in 1998, and her maths teacher father died in 2004.

She recently lived in a £145,000 two-bedroom flat in Acton, west London.

According to her LinkedIn profile, Ms Sutton – who studied at Strathclyde and Warwick universities – also worked for the United Nations and was a producer and broadcaster for BBC World between 1998 and 2000.

After graduating from Warwick, she spent two years in Canada before retuning to London to study for a Masters when she became involved in the City of London Anti-Apartheid Group and worked for the Angolan Embassy.

She then worked for the UN International Fund for Agricultural Development in Rome, where she also presented news on Vatican Radio.

She was encouraged to travel to Eritrea by a contact she met on the radio station, and spent five years there from 1993 to 1998, during which time she met her husband Charles.

Destination: Ms Sutton is believed to have been the acting Iraq director for the Institute for War and Peace Reporting, and was on her way to Erbil (file picture) in Iraq

They married in 2000 but separated in 2003 and divorced a year later because of their opposing views over the invasion of Iraq.

She later worked in Afghanistan and Iran, but had to flee to Ghana after she helped a British friend arrested on suspicion of murder leave Afghanistan.

Sutton then spent several years working for the UNDP in Iraq before moving to Australia, where she was studying for a PhD before her death.

Lebanon-based Jessica Dheere said she was devastated at the news, which comes after the death of the IWPR's director Ammar Al Shahbander, who was killed in a car bomb attack in Baghdad in May.

She tweeted: 'Incredibly distraught about death of 2nd #IWPR #IRAQ director in 6 mths. #RIP Jacky Sutton. U were a force.'

Ms Sutton, who spoke five languages including basic Arabic, had been studying for a PhD at the Centre for Arab and Islamic Studies at the Australian National University.

Her research was on international development support to female media professionals in Iraq and Afghanistan between 2003 and 2013 and had been carrying out field work in Erbil, Iraq, since July.

He also said that missing her flight would not prompt such an extreme reaction in such an accomplished woman when asked if it could have led to her suicide.

'No, that's impossible...we're not talking about a girl. She's a woman, an official woman, she's a big manager.'

A fierce warrior for justice and equality Liz Mulhall, friend

Mr Elias said there was no reason anyone would want to kill her, and the most confusing part of the tragedy, he said, is that it happened in Turkey.

He added: '[Iraq] is a very dangerous place... there are many problems, and the security situation is bad, so if something happened against a foreign person... but in Turkey, it's really, really confusing.'

Liz Mulhall, who works for an Australian charity that raises funds to support the UN Refugee Agency, tweeted: 'Rest in peace Jacky Sutton.

'A fierce warrior for justice and equality and a true friend.'

Meanwhile, World Food Programme representative Jane Pearce said: 'Mourning my friend and colleague Jacky Sutton tonight. Simply don't believe the news reports.'

She was among acquaintances who expressed doubt at reports in Turkey of the unusual circumstances leading up to Ms Sutton's death.

Professor Amin Saikal, centre director for Arab and Islamic Studies at the Australian National University, said everyone was 'deeply saddened and shocked by the tragic death of one of its brilliant PhD students'.

Prof Saikal added: 'She was not only an outstanding research scholar, but a highly valued friend and colleague who made remarkable contributions to the work and activities of the centre.'

A Foreign Office spokesman told MailOnline last night: 'We can confirm the death of a British national in Istanbul. We are providing consular assistance to the family at this difficult time.'

It comes just five months after the previous IWPR Iraq director Ammar Al Shahbander was killed in a car bomb attack in Baghdad. A memorial service was held for him in London last Tuesday.