Friends and colleagues of a British journalist and international development worker who died in Istanbul have described her reported suicide as "impossible to understand", saying she had "lots to live for".
Jacqueline Anne Sutton, 50, known as Jacky, was found dead at Ataturk Airport after flying from London on Saturday night.
The 50-year-old was the Iraq country director for the Institute for War and Peace Reporting (IWPR), which said it was "devastated" at her death.
Ms Sutton was appointed to the role at the end of June following the death of her predecessor Ammar Al Shahbander, who died in a car bomb attack in Baghdad in May.
Anthony Borden, executive director of the IWPR, called for an "open and transparent" investigation into her death - which was reported as suicide by Turkish media outlets.
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.
"There's a matter of boot laces - I'm not even sure the boots she was wearing even had laces. If she wasn't wearing laces, how did she kill herself using boot laces?"
"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.
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."
Ms Sutton had been in London to join Mr Al Shahbander's family, friends and colleagues at a memorial service for him at St Bride's Church in Fleet Street last week and was due to catch a connecting flight from Istanbul to Erbil, according to the IWPR.
Mr Borden said Ms Sutton was in "high spirits" when they had lunch last week and that Mr Al Shahbander's 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.
Ms Sutton had worked as a producer for BBC World Service from 1998 to 2000 and served with the United Nations in numerous senior roles that took her from Afghanistan and Iran to west Africa and Gaza.
Iraqi journalist Mazin Elias, who had worked with Ms Sutton, told MailOnline it was "impossible" that she killed herself.
Mr Elias said "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."
Ms Sutton was a "big manager" who was unlikely to have missed her flight, 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."
Mr Elias alleged Ms Sutton could have been killed. "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 said.
Mr Borden earlier said IWPR was in "total shock" following the death of Ms Sutton.
He added: "She was extremely bright, highly competent, and well able to handle herself in difficult environments, and she was universally loved."
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 she had been carrying out field work in Erbil, Iraq, since July.
Centre director Professor Amin Saikal said people at the university are "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."
Journalist and international development worker Rebecca Cooke 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."
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."
Lebanon-based Jessica Dheere said she was devastated at the news.
She tweeted: "Incredibly distraught about death of 2nd #IWPR #IRAQ director in 6 mths. #RIP Jacky Sutton. U were a force."
The Foreign Office confirmed it is providing consular assistance to Ms Sutton's family.