In September 2008 the extrajudicial killing of 11 young innocent men from a slum near Bogota by Colombian army soldiers shocked the nation. In this picture a protest march in Bogota commemorates the first anniversary of the killings.

A prosecutor from the Medellin Human Rights unit of the attorney's general office on a four-hour walk to excavate and unearth the body of a man killed in 1997 by the FARC (Revolutionary armed forces of Colombia), the main left wing guerrilla group.

In the town of Balboa, a judicial Investigator from the Medellin Human Rights unit has set up his typewriter on an altar in a chapel by the cemetery. He is taking the statement from the brother of a man killed by paramilitaries in 1996.

A forensic anthropologist seals off a crime scene before starting the exhumation process. On a remote hill two hours walk from the nearest road, the remains of a man were found. A woman present during the exhumation is certain the remains belong to her son when she learns that no skull was found. She was told that her son's paramilitary assassins were seen playing football with the head.

This woman was a witness to the 1988 massacre of miners at the River Nare.  She saw ten miners handcuffed and abducted by soldiers in civilian clothing. Fourteen or 15 people were killed.

A football shoe dug up at this site provides this woman with evidence that the human remains are those of her husband who disappeared in 1997 on his way to a football match. He was allegedly killed by FARC guerrillas.

Relatives of victims stand by the entrance of the cemetery of San Luis to watch the remains exhumed and transported to the laboratory for identification.

A son holds a picture of his missing father. Information that the man was assassinated at the family farm led to the discovery of a pile of bones. On closer inspection, the Medellin Human Rights unit found them to belong to an animal.

The blanket in which the headless remains of a man was found at Vereda Cristalina.

According to a prosecutor from the Medellin Human Rights unit, the local parish moves the remains in unmarked graves to a collective grave to create space for new cadavers. The practice greatly reduces the chances of identifying the victims, since DNA testing in Colombia is not systematic but selective due to the lack of resources.

At the cemetery of Carmen De Atrato the Medellin Human Rights team finishes the exhumation work on an unmarked grave. Before the evidence is sealed all remaining bones are counted and described. A DNA test will be carried out and the results crosschecked with the DNA of possible relatives.

A Medellin Human Rights unit consists of a prosecutor, a forensic anthropologist, a photographer, a topographer, a judicial investigator and a ballistics specialist. Here they are exhuming remains in the cemetery of Balboa.

At the cemetery of San Luis clothing and personal items are displayed in front of the families of the victims for recognition before they are packed and sealed. Often relatives recognize these items although this has no validity as an official proof of identity. DNA finger prints and a dental chart are the only methods accepted.

In Medellin at the forensic laboratory of the Human Rights unit, the clothing found on victims is washed and photographed for publication online.

At the cemetery of San Luis the father of two assassinated sons takes the bag containg the remains of one of the bodies to the van of the Medellin Human Rights unit. At least another year will pass before the remains will officially be handed over to the families of the victims.

Family members are briefly allowed to view the package containing the remains of a man killed by FARC in 1997.

At the forensic laboratory of the Human Rights unit in Medellin, forensic scientists are processing hundreds of cases. It is thought that some 50,000 civilians killed by right-wing paramilitaries, state agents and guerrilla groups lie in unmarked graves scattered across the country.

The group of relatives of the victims of the miners massacre watch the exhumation process. The woman wearing glasses in the front row recognised the rubber bracelet of her son. The 15-year-old boy was visiting his uncle, a gold digger, when he became a victim of the massacre.