All journalists have sources, but some sources become friends.
For me, one such was Alison Des Forges, a historian of Rwanda. I happened to be living in Kigali when the genocide started in 1994.
Alison, who taught history at Buffalo University and advised Human Rights Watch, became an invaluable source because she had studied the region for three decades.
She was a small, grey-haired, determined and wonderfully generous person.