Bedazzled by DNA - is it enough to convict?

Boettcher says when he examined the graphs of the DNA profiles the DNA from the male blood at the scene seemed to have deteriorated more than Marshall’s. “There is a chance the greater deterioration of the DNA in the male blood was due to it being deposited some days earlier than Marshall’s murder.”

However, Prosecutor Paul Rutledge described the numbers provided by Cox as “awesome”. “Fitzherbert has left traces of himself at the scene of Kathleen Marshall’s murder … the man who left the blood in that surgery is guilty of the murder.” This is what is known in the profession as the “prosecutor’s fallacy” - the fallacy being that the rarity of the DNA profile is equated to the likelihood of guilt.

In his summing up, Justice Ken MacKenzie said: “You would exclude as unreasonable on the basis of the scientific evidence any suggestion that someone else may have left the blood at the scene and you would therefore be satisfied beyond reasonable doubt that the accused was the killer.”

There was, in effect, no evidence whatsoever that the man who left the blood in the surgery killed Marshall. And as defence counsel Jeff Hunter pointed out, Fitzherbert had a rock solid alibi for Friday night. If the evidence of the alibi witnesses was to be accepted, there was simply no opportunity for the accused to commit the murder, and what was conspicuously absent was a motive. Hunter cautioned the jury from being prejudiced by the fact that Fitzherbert was an eccentric middle-aged man, who might be a bit strange and a bit weird, and who holds some [spiritualism] views they might find odd.

Rutledge described the DNA evidence as going “cleanly, directly to the heart of the matter”, and said Fitzherbert was a liar, reminding the jury they’d been given the “expert evidence” of a scientist compared to the “garbage bin of the sciences of palmistry”.

It took the jury less than four hours to decide Fitzherbert was guilty. In sentencing him to life imprisonment, Justice MacKenzie said to Fitzherbert, “This is a crime of which you would not have been convicted but for the recent explosion in knowledge in the field of genetics”.

However, Bond University’s Chair of Criminology Professor Paul Wilson points out that DNA evidence is not infallible, as most people think. “Forensic Science is part art, part science. It’s very, very dangerous to convict purely on forensic science evidence and even with DNA evidence there can be problems. How DNA is collected, transported, stored, analysed, interpreted can lead to errors and miscarriages of justice.”

After the trial a spokesperson for the Cat Society said the group was pleased there’d finally been closure. Marshall’s lawyer Ian Galton said the verdict brought to an end an “awful situation” for the family. “At least we got justice at the end of the day.”

Fitzherbert appealed his conviction in March 2000 and acted for himself. He was unsuccessful.

For the last nine years, Bennett has visited him in prison almost every week. “At the time, it was like, I don’t believe this is happening. It was surreal. I thought we had a justice system in Queensland, but it turned out to be just who puts up the best argument in court. My life has been on hold ever since. They virtually put me in prison too.”

Fitzherbert had the right to retest the blood samples at the government’s expense at the time of his trial and at his appeal, but was not made aware of that right. Since 2003, Cameron-Dow has made several requests to the Queensland Attorney-General to release crime scene samples for testing.

Attorney-General Kerry Shine wrote to Cameron-Dow in May this year and said he wouldn’t allow further testing as all items had been tested, and there was nothing wrong with the DNA testing method. Cameron-Dow claims not all items were tested and Cox admitted this. She says she made no allegations about the testing method, only Cox’s analysis of the results. Cameron-Dow is appealing the Attorney-General’s decision. If unsuccessful, the only recourse after that would be a request to the High Court for permission to retest crime scene samples or to review the case.

In some countries it is mandatory that convicted people have access to samples. Cameron-Dow says it should be Fitzherbert’s right to retest. “Is the Attorney-General saying that because Fitzherbert has been convicted, he can no longer attempt to prove his innocence at his own expense?”