Botero is the daughter of an architect/designer and of an ecologist. She attended the Juan Ramón Jiménez secondary school in Bogotá and received her law degree in 1988 from the University of the Andes.
While a student, Botero was a leader of the "Septima Papeleta" (Seventh Ballot) Movement, which called for the convocation of a National Constituent Assembly in Colombia in 1991.
After receiving her law degree, she went on to do postgraduate studies in Public Management and Administrative Law at the same university. She continued her postgraduate work in Madrid, where she studied human rights at the University Human Rights Institute at the Universidad Complutense (1990–91), studied constitutional rights and political science at the Center for Constitutional Studies (1992), and received a degree in advanced studies (DEA) at the Universidad Carlos III.
The Inter-American Commission on Human Rights (IACHR) elected Botero as Special Rapporteur for Freedom of Expression on 21 July 2007. She took up the position in July 2008.
In August 2010, Botero and Frank La Rue, a UN Special Rapporteur, made recommendations to the Mexican government regarding freedom of expression and access to public information. They stated that Mexico is the most dangerous country for journalists in the Americas. They also criticized the fact that impunity is widespread in Mexico, that free expression is limited by federal and state laws, that there is lack of media plurality, and that access to public information is increasingly restricted.
In a 2011, Botero wrote an article titled "Freedom of Expression in the Americas," which observed that while Latin American military dictatorships had given way, in large part, to democracy, a "culture of secrecy" remained in place, as did "restrictive press laws." He claims that while "the region faces a number of major challenges," including the protection of journalists, the decriminalization of speech acts, access to information, direct and indirect censorship, and pluralism and diversity in the public debate.
In 2012, after Botero criticized attacks on the news media by Ecuadorian President Rafael Correa, he joined Venezuelan President Hugo Chávez in dismissing her criticism of their governments and submitting a proposal to the OAS "to review the freedom of expression office and limit its jurisdiction."
On 22 March 2013, El Comercio (Peru) reported that Botero had expressed concern over restrictions on the commission and its funding that had been proposed by Ecuador, saying that it should have "a permanent fund...that would allow the commission to completely fulfill all its responsibilities." Otherwise, she warned, the Special Rapporteur's office would have to be closed.
In January 2008, she took part in a seminar on "Media and Government," arranged in Washington, D.C., by the Inter-American Dialogue. In 2012, she was the keynote speaker at a Mexico City event entitled "Change Your World," sponsored by Yahoo!, at which women from around the Americas gathered to discuss and exchange experiences and ideas relating to human rights and technology.
In 2016, Marino, along with a group of Colombian lawyers, the Global Freedom of Expression project at Colombia University, UNESCO, Dejusticia, and The Foundation for Press Freedom, created the Freedom of Expression Case Law online database,allowing access to information of the highest courts of 16 Latin American countries.