Why are Twitter and Instagram users turning their profiles blue?

Mohammed Hashim Mattar was just 26 when he was gunned down by Sudanese security services last week.

Now his favourite shade of indigo blue has become a symbol of the country’s embattled pro-democracy uprising.

Thousands of social media users have switched their Instagram and Twitter Avatars to the same colour, using the hashtags #blueforsudan.

“It started off with the friends and family,” said Amal Amir, a British-Sudanese social media user who has taken part in the protests. “It’s his favourite colour and it was his display picture on all his social media accounts. Then it started being for all martyrs.”

What happened?

Mattar, a graduate of Engineering Management at Brunel university, was one of dozens of people shot, beaten, and stabbed to death when Sudanese security forces brutally cleared a protest camp in central Khartoum in the early hours of June 3.

No one knows exactly how many people died but the Sudanese Doctors’ Committee, which is part of the protest movement, on Wednesday released the names of 112 people confirmed dead.