The most common method of investigating pathology is to take biopsies (samples) of tissue suspected to be diseased or injured and looking at it under a microscope. Examining tissues under a microscope is termed histology, hence the name histopathologist given to hospital pathologists.

Histopathologists can also undertake autopsies (or post mortem examinations) in cases where a patient has died without a specific cause of death being known.

An autopsy (also known as a post mortem as it is the examination which is carried out post mortem or after death) consists of an external and internal examination.

During the external examination, the general features of the body, e.g. height, build, hair colour age and so on, are recorded along with any scars (medical or otherwise) and signs of medical intervention, e.g. electrocardiogram electrodes, catheters etc. Any signs of injury or disease visible externally are also recorded however, if during this examination the pathologist believes there to be any element of suspicion as to the nature of the individuals demise, he or she will pass the case over to a forensic pathologist. (The role of the forensic pathologist is discussed in more detail below)

During the internal examination, all of the anatomical systems are examined in detail for signs of disease or injury and the observations are recorded.

Further investigations can also be carried out to aid in establishing the case of death. These include histology (as described above), where tiny samples of tissues from the main organs are examined under the microscope in order to pick up evidence of disease or trauma that is not visible to the naked eye, and toxicology, where samples of blood, urine or muscle are tested for chemical substances such as alcohol, street drugs or prescribed drugs.

The cause of death, if established, can then be made known to the coroner.

To become a forensic pathologist you must undergo further training and become registered by the Home Office.

Forensic pathologists, along with the expertise of a histopathologist, are trained to work on cases with a medico-legal or criminal aspect to them. They can therefore take on cases of suspicious deaths such as suspected murders or manslaughters or deaths which may have legal aspects such as post operative deaths where clinical negligence, for example, may need to be ruled out or confirmed.

Forensic pathologists deal with cases that are not only concerned with establishing a cause of death, but in which all observations may be used as evidence in a court of law.

A forensic pathologist can be called to the scene of a crime at any time of day or night by the police to aid in their investigation of a suspicious death. This scene visit enables the pathologist to begin building a background to the case and to take any samples required before the body is moved. He or she will then have to carry out a forensic autopsy on the body of the deceased. Before the forensic autopsy begins the known facts of the case are discussed by the investigating police and the forensic pathologist.

The forensic autopsy includes a more detailed external examination during which every area of trauma (injury ranging from a scratch to cranial fractures or internal haemorrhage (bleeding)) is analysed and recorded.

Trauma may also be present internally (for example stab wounds or internal bleeding from blunt force) and, therefore, along with a detailed examination of the organ systems, internal trauma must be examined and recorded.

Histological and toxicological examinations (as described above) are more common in forensic autopsies and may play a key role in determining the cause of death.

The forensic autopsy not only aids in the determination of the cause of death, but also the manner in which the deceased came to his or her death.

The information gained from the autopsy can then be cross-referenced against other evidence and witness statements to allow a clearer picture of the events to emerge.