KARACHI, Jan 10: Preservation of a crime scene and documentation of every bit of information available there are the two most important pillars of an investigation. If based on physical scientific evidence, such an investigation is taken seriously in an international court of law and can help the prosecution win its case.

This was the gist of Professor Dr Omar Bagasra’s lecture, Crime Scene Investigations and Forensic Studies, which he delivered at Karachi University on Saturday. An eminent molecular biologist, retro-virologist and immunologist, Dr Bagasra is currently serving as director of the Centre for Biotechnology, Claflin University, South Carolina, USA. The programme was organised by Karachi University’s Faculty of Science.

Highlighting the significance of collecting physical evidence in any crime investigation, Dr Bagasra said: “If an investigator cannot recognise physical evidence and preserve it accordingly, no amount of sophisticated lab instrument or technical expertise can salvage the situation. It also needs to be emphasised that the techniques of crime scene investigation are not difficult to master and certainly lie within the reach of an average police officer.”

He said that forensic science was applied right from the collection of physical evidence at a crime scene. Depending upon the nature of the case, the evidence gathered was then preserved in a scientific manner with utmost care to eliminate any risk of contamination till it’s handed over to the relevant lab.

“Crime labs run on physical evidence. Without it you can’t do your job. This takes precedence over the account of an eyewitness that is given only a three per cent chance of accuracy in a case, because human observation is limited.”

The single most important step in a crime investigation was to secure the crime scene, he said, and added: “Obtaining medical assistance for any victim, of course, takes priority as nobody will blame you if you lose any evidence while saving a life. But once this process is over, the priority must be given to secure the crime scene and every effort should be made to exclude the entry of all unauthorised persons.”

He said that recording of a crime scene had become much easier with the use of digital cameras and other technologies. “Second step is to document every bit of information available at the site, for instance, time of the offence and your arrival, date, location as well as weather conditions. A DNA analysis is the last resort and most cases are solved without carrying out this procedure,” he added.

He said that search for physical evidence must extend beyond crime scene to the autopsy room. Besides, he said, a lab examination was of great help in determining the cause of death.

However, he observed that the acquisition of physical evidence should not be considered 100 per cent accurate, as there were always chances of error.

In this context, he referred to the Madrid train bombing case that killed 191 people in 2004. During the investigation, a US lawyer, a Muslim convert, was arrested when part of fingerprints evidence collected from the site matched with the fingerprints of the suspect. “The man, who was subjected to severe torture, sued the Federal Bureau of Investigation (FBI), which was helping the Spanish police in investigation.

“He was later proved innocent and the FBI had to pay millions of dollars in damages,” he said, adding that this showed that weaknesses in the system could lead to denial of justice.