Mike Haines described the conviction of El Shafee Elsheikh in a US court as a "triumph for society over the ills of terrorism and extremism".

David, an aid worker from Perth in Scotland, was taken hostage by Islamic State (IS) in Syria in 2013.

The 44-year-old was taken hostage when a convoy he was travelling in was ambushed - and was then beheaded by his captors, who posted footage of his execution online.

Read More: Aid worker taken hostage with David Haines tells court of 'intense' beatings

Mike said: "He was dragged at gun point from the vehicle, beaten senseless, thrown into another vehicle and driven off.

"I was at my home in Dundee when I got the phone call telling me of David's kidnapping. Having to tell our family was the hardest thing I had ever done, it was what I thought was going to be the worst night of my life.

"Then, a year and half later, David was murdered by ISIS in a video that was laid out for the world to see. His murder was an act of hate, designed to sow hate, sow division, sow discord.

"I have never seen the video and I will not see the video because it is a propaganda production."

'I have never felt such strong hatred or anger'

Mike learned of his brother's death on the 13 September, 2014.

"It was a beautiful day and we'd filled it full of family love and laughter and hope that my brother would come home safe.

"I was sat on the side of my bed undressing and my phone began to ring. I felt so much horror, so much trepidation, so much anguish and despair as I knew it was the call I'd been dreading since day one."

"It was 3 minutes past 11 and I had my team leader in London telling me that David had gone. I felt so much anger, so much hatred.

"If I could have run away from telling my family, I would have done, but I couldn't let it be a stranger. I got my family together, I took my Mum's hands and told her (that) her son couldn't be hurt anymore.

Read more: Widow of David Haines calls for captured IS jihadis to reveal location of body

"I have never felt such strong hatred or anger. If somebody could have flicked a switch and the people who were involved in the murder of my brother were at my feet kneeling unarmed, I would have put a pistol to their head. I would have murdered them, and that shocked me.

"So I tried to think what was the act of murdering David about. The point that hit me was that his murder was about the spread of hate.

"What they wanted was for me to stand up and point the finger at Islam and that would have just caused more division. Islam is a faith of tolerance, it's a faith of understanding, it's a faith of compassion. It's about ISIS's terror, death, murder. If we hated, they win."

'Justice was not something ever afforded to my brother'

El Shafee Elsheikh was one of three so-called 'Beatles' responsible for the kidnapping, torture and murder of more than 20 international hostages. As well as David Haines, they included UK aid worker Alan Henning from Salford in Greater Manchester. John Cantlie, a British journalist who was seized in 2012, remains missing.

In the wake of his brother's killing, Mike Haines launched Global Acts of Unity, a campaign promoting unity, tolerance and understanding in schools.

Of Elsheikh's conviction in the Virginia courtroom, he said: "It brings to a close a nine-year-long chapter of pain for my family. Justice was not something ever afforded to my brother or others who were killed by these men, but it's only right that we put these men on trial for their crimes.

"By successfully trying and convicting these men of their crimes, it's a triumph for society over ills like terrorism and extremism. A long prison sentence will, hopefully, deter others from following this same path."