James Gill, the chief medical examiner for the state of Connecticut, will give a lecture in Dunedin today on
''Forensic Pathology in the United States: Death, drugs, and disasters''.
Criminals had escaped prosecution for some crimes, but there was ''always something'' unexpected which made it very difficult to carry out the ''perfect'' murder, he said.
A motorist driving past could see something, and small but telling pieces of evidence could be left behind.
In every murder ''there's one unbiased witness, and that's the decedent''.
''It's our job to interrogate that witness,'' he said.
Dr Gill yesterday met Dr Angela Clark, who is co-ordinating a forensic biology paper, the most popular paper at the university's latest summer school.
This popularity showed that forensic science and pathology were being viewed positively, he said.
Careful analysis enabled accurate records and statistics to be maintained, and the related research also had important public health implications, by highlighting threats to community health and safety.
Some popular crime-related television programmes, including the CSI series, were raising awareness about forensic pathologists.
''It gets people interested in the field, which is a good thing.''
One potential problem arising from such TV shows was jurors sometimes found there was no DNA and little of the other physical evidence they were used to seeing on television.
