Kathryn Sikkink in the New York Times:
My research shows that transitional countries — those moving from authoritarian governments to democracy or from civil war to peace — where human rights prosecutions have taken place subsequently become less repressive than transitional countries without prosecutions, holding other factors constant.
By comparing countries like Argentina and Chile that have used human rights prosecutions with those like Brazil that have not, I found that prosecutions tended not to exacerbate human rights violations, undermine democracy or lead to violence.
Of 100 countries that underwent a transition from 1980 to 2004 (the period for which extensive data is available), 48 pursued at least one human rights prosecution, and 33 of those pursued two or more. Countries that have prosecuted former officials exhibit lower levels of torture, summary execution, forced disappearances and political imprisonment. Although civil war heightens repression, prosecutions in the context of civil war do not make the situation worse, as critics claim.
The piece is here. Here is some of her related research (pdf).