David Haines, a 44-year-old father of two apparently killed by Islamic State militants, had a career which had taken him to crisis hotspots around the globe.

Mr Haines, originally from Perth in Scotland, was kidnapped last year while working for the French aid agency ACTED in Syria.

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“David has been working as a humanitarian since 1999, helping victims of conflict in the Balkans, Africa and the Middle East,” ACTED said on its website shortly after it was revealed he was being held hostage.

“A man’s life should never be threatened on account of his humanitarian commitment.”

After 11 years in the military, Haines offered his security expertise to various development NGOs.

According to his online LinkedIn profile, these included a German aid group, Arbeiter-Samariter-Bund, which helped refugees from the Balkans war return to their homes; Handicap International, where he headed up a mine clearance and education program in Libya; and a civilian peacekeeping NGO Nonviolent Peaceforce, where he managed security and risk assessments in south Sudan.

The profile said he also worked for Military Sales and Service, a US-based company which represents manufacturers which sell their goods to the military, and managed a restaurant supplier business in Croatia.

At ACTED, he helped coordinate the delivery of clean water, food and tents at refugee camps near Atmeh, in northern Idlib province, according to the BBC.

In a statement released by the British Foreign Office, Mr Haines’s brother Mike remembered a man who was “most alive and enthusiastic in his humanitarian roles”.

“His joy and anticipation for the work he went to do in Syria is for myself and family the most important element of this whole sad affair,” he said.

This is the man IS murdered. If you are going to share a picture of #DavidHaines make it this one. #aidworker #dad pic.twitter.com/ji1kqivyhL

— anita anand (@tweeter_anita) September 14, 2014

Mike Haines said his brother “was and is loved by all his family and will be missed terribly”.

“David was a good brother, there when I needed him and absent when I didn’t. I hope that he felt the same way about me,” he said.

“He was, in the right mood, the life and soul of the party and on other times the most stubborn irritating pain in the ass. He would probably say the same about me.

Mr Haines had married twice and had one daughter, aged 17, from his first marriage and a second daughter, aged four, from his marriage to a Croatian woman named Dragana, with whom he lived in Zagreb, Croatia, according to the Telegraph newspaper in the United Kingdom.

“He’s everything to us. He’s our life. He’s a fantastic man and father,” Dragana told the newspaper shortly after Islamic State militants threatened to kill him.

“Nobody can understand how we are feeling. My daughter keeps asking about him every day. She hasn’t seen her father for a year and a half. She has gone through so much. She sees me crying all the time.”