On November 22, 1983 Lynda Mann 15 was found murdered only a few miles away from her home. It was not immediately evident who had committed the crime. The police were unable to come up with any leads to catch the offender, but he had left a bit of evidence behind. The killer rapist had left a small sample of his semen. Four years later on July 31, 1987 Dawn Ashcroft, also 15 years old was raped and strangled to death. The similarities between the two cases were too evident to ignore. The police believed that the same man had committed both crimes.
A massive man hunt began to find the killer, but it seemed that none of the people they interviewed were likely suspects. The policemen got a break when some one mentioned that a young dishwasher was a possibility.
The dishwasher was subjected to a lengthy police interview. At first he denied any association with the crime but after extensive questioning he admitted to the crime although his testimony was incoherent and often contradictory. Although he admitted to the murder of Dawn Ashcroft he would not admit to the murder of Lynda Mann. At this point one of the policemen had an inspiration. He had read in a magazine about new forensic technique called DNA fingerprinting (later renamed DNA profiling). It had not been used to solve a case yet but it seemed like a good chance to prove the dishwasher’s guilt. The technique was developed by English geneticist Alec Jeffreys. It enabled the investigators to compare the suspect’s DNA with the DNA from the semen found at the crime scene. After the results came in, the police were surprised to see that the DNA testing proved that the dishwasher was innocent of both murders. However, they realized if it could prove one man innocent it could prove another’s guilt.
A massive DNA profiling of every person who could have committed the crime or did not have a strong alibi began. Months passed and hundreds of DNA profiles were taken from blood samples and given to the neighbourhood police, but none of them matched the semen found on the bodies of the two girls. Then the big break came. A young woman who managed a local bakery mentioned she had overheard a man confessing to another that he had paid someone to go in his place to give blood in his name. The man was named Colin Pitchfork. Pitchfork had a record and had been arrested several times for indecent exposure. The police confronted Colin Pitchfork with the murder accusations and being convinced that the DNA identification would show up positive, Pitchfork admitted to both crimes. A DNA sample was taken from Colin Pitchfork and it was a match. He was guilty of the rape and murder of both girls.
Wee Waa, Australia
A similar case occurred in Wee Waa involving the rape and bashing of a 93-year-old woman. Following a year long investigation the decision was made in April 2000 to try a mass DNA testing program. The appeal for Wee Waa men to voluntarily submit to saliva DNA swab tests is a last throw of the dice for police investigating the attack that took place in the pre-dawn hours of New Year’s Day 1999.
The attack, which occurred inside the woman’s childhood home came after an intruder cut power to the premises. The woman was almost suffocated with a pillow during the assault, and has since sold the home and moved into a nursing home.
Farm labourer Stephen James Boney, 44, was among 500 men in the north-western NSW cotton-growing community who took part in the controversial police DNA testing. Police, including 30 extra officers from Sydney, spent a week asking Wee Waa males aged 18 to 45 to voluntarily give saliva samples. Throughout the period of testing intense debate raged about the issue of DNA testing.
The father of three and former local rugby league player, who settled in Wee Waa in 1990 after moving from Brewarrina, had been among a dozen suspects targeted by police, but police had nothing to link him to the case other than DNA collected at the scene of the attack. From day one he could have refused the test.
Ten days after submitting to the test, as police waited for the results of the samples to come back, Boney suddenly entered Wee Waa police station, saying he wanted to confess, that the pressure from the inevitability of eventually being caught by DNA had got to him.
In a brief appearance before Moree Local Court, Boney pleaded guilty to the rape.
There have been many convictions using DNA profiling but care must be taken in interpreting the results. In April 1999 a man in Britain was arrested for a burglary on the basis of over confidence in DNA profiling in the face of contradictory evidence. Initial testing at 6 loci of samples from the crime scene had matched the man’s DNA profile. Later testing at 10 loci showed exclusions and the man was released from custody. While the testing system in Britain is different to that in Australia, DNA profiling is only one tool in the investigators armoury and investigators should not be blinded to the value of other evidence by this latest technological advance.
Of course forensic science does not just implicate but can also eliminate. Most notably DNA profiling has successfully been used in America to get a number of people off death row.