How Forensic Expert Witness Testimony Can Convince A Presiding Jury

Forensic expert witness testimony can help to convince a jury that a defendant was at the crime scene at the time in question, or, in the case of electronic testimony, that they had the relevant files stored on their computer. The science of forensics has advanced a long way since the early days, before the advent of the twentieth century, when isolated cases were decided on evidence which had been found at the scene of the crime. In those days, the term "forensics" had not yet been invented, and it would be the early years of the twentieth century when the science would start to be seriously used.

Pioneers in forensics were quick to spot the potential for fingerprints to be used to place people at the crime scene. This followed a celebrated case in Argentina when a suspect was convicted of murder due to leaving a bloody fingerprint at the crime scene. If a technique could be developed where a fingerprint could be identified without the need for blood to be present, what could this do for crime detection? Now, even though professional criminals avoid leaving fingerprints, many amateur or opportunist criminals are still caught this way.

There are many other ways in which body matter left by a criminal at a crime scene can become conclusive witness testimony. Blood can often be left at a crime scene if criminals are disturbed in the act, and DNA is nearly always left. The use of DNA evidence in court remains highly controversial, and there are DNA techniques which have been banned from use in a USA court. Vehicle tracks and footprints can also form a vital part of witness testimony, so long as they are supporting evidence.

One of the newest forms of expert witness testimony is from forensic experts dealing with computer technology. Many criminals store information on electronic systems, and even communicate electronically. A computer forensics expert can study electronic systems to see if there is any residue of data left in the system. Because computer operating systems do not actually delete data when the Recycle Bin is emptied, it can be retrieved by accessing the memory addresses directly.

For this type of forensic expert witness testimony to be effective, it needs to be provable in court that the data was actually in the computer system at the time it was analyzed. Without this, there is always the possibility that evidence had been tampered with. The same applies to computer forensics applied to a cell phone, which will also store and delete files in a similar way. Many people in all walks of life are careless with cell phone use, and even criminals are not immune to this. Extremely damning evidence can be brought into court by a forensic expert witness.