Maresha Mammo is one of the founders of the independent Ethiopian newspaper Addis Neger (New Thing). Since its foundation in 2007, Addis Neger published critical articles about the government. As one of the few independent newspapers in Ethiopia, practicing critical journalism with credible and researched viewpoints, it rapidly gained popularity in the public sphere as a rising free voice, and reached out to a new and different audience.
In the aftermath of a chaotic 2005 election, the Ethiopian government shot down 200 peaceful protesters and 40.000 were imprisoned. Addis Neger issued several stories prior to the 2010 election about the challenges and unlikeliness, as in 2005, of a successful and fair election in the coming year.
The newspaper received public threats and was informed that the government would close it down. In late 2009, the Ethiopian government prepared criminal charges that entailed heavy imprisonment against all six co-founders of the paper, including Masresha Mammo. Masresha Mammo arrived as a guest writer in Amsterdam in May 2013.
Addis Neger Online is still alive on Facebook.