The fence in your head - Amnesty International & mentalgassi take to the streets for death row prisoner Troy Anthony Davis

The latest Amnesty International campaign is the result of a creative collaboration between London agency Brothers and Sisters and the Berlin Street art collective Mentalgassi, which went forth and 'decorated' several fences in central London with their characteristic installations.

'Making the invisible visible' looks to make the work of Amnesty International more conspicuous, fighting for human rights, including their campaign against the death penalty and the rights of innocent convicts.

A particular case is 42-year-old American Troy Anthony Davis, whose face adorns the installations of Mentalgassi. For 19 years, Troy has been confined in death row in the state of Georgia, for a murder, which he insists he has not committed, for 19 years.

Amnesty points out that there are is no impartial evidence which connects him to the murder and over the last seven years, nine witnesses – whose statements were implemental in Davis' conviction in 1991 – have been withdrawn and changed in favour of him respectively.

Despite all doubts hovering around the conviction, Davis is still being held awaiting execution.