The Aga Khan, spiritual leader of the Ismaili Shia Muslim community and known for his development work around the world, has died in Lisbon aged 88. According to the Aga Khan Development Network, an announcement to designate a successor to Karim al-Husseini, as he was known, will take place soon.

Aga Khan, spiritual leader of the world's Ismaili Muslims, died on Tuesday in Lisbon, Portugal. He was 88. Khan, who was born Prince Shah Karim Al Husseini, assumed leadership at 20 while studying at Harvard and led the global Ismaili Muslim community for over six decades.

Hussaini, son of Prince Karim Al-Hussaini Aga Khan IV, has been named in his father’s will as his successor to lead the Nizari Ismailis, a Shia Muslim denomination. We take a look at this branch of Shia Islam that has 15 million members worldwide.