SEE-THROUGH plastic bags, tweezers of varying sizes and pristine white boiler suits: these are the tools and the regulation uniform of the State's team of evidence gatherers and forensic scientists who ply a gruesome but vital trade. Our men, and women, in white have been kept busy over the past few decades. Murder after murder, rape after rape, they have combed the scenes of crime searching for specific evidence such as blood, semen, stray hairs or clothing fibres.
Much of the time they do not know what they will find to eventually link a murder to the guilty party. The crime scene is like a complex jigsaw puzzle. It can take months, even years for the pieces of forensic evidence to fit neatly together, but more often than not it is this evidence that convicts.
As head of the Forensic Science Department at Garda Headquarters, Dr Jim Donovan has been on the front line of this activity for almost 25 years. Last week he took The Irish Times through the often grisly forensic evidence that has helped solve some of the most high-profile crimes committed during that period.
In 1975 Garda Michael Reynolds went into a bank in Killester, North Dublin, to cash a cheque and rumbled a bank robbery. The robbers fled and Garda Reynolds gave chase into St Anne's Park, where he was shot dead by one of them. The main pieces of forensic evidence that were found to convict the husband and wife who were eventually found guilty of his murder were traces of the false facial hair they had used as a disguise.
The hair was fixed to their faces with theatrical glue, which had dripped everywhere. They had worn woollen gloves to avoid leaving fingerprints when applying the glue, and traces of it were found on the body, on their car and in a toilet in Dun Laoghaire where they had tried to dump the clothes they had worn.
A missing button on the woman's coat also proved crucial. At some stage during the murder, Garda Reynolds had tugged on the woman's coat and dislodged a button, the thread and cloth attached to it. The material and button found on the ground in St Anne's Park beside the Garda's body matched the hole in her coat where the button should have been. The couple were sentenced to life imprisonment but have since been released.
Deborah Robinson from Belfast came to Dublin on a blind date in the summer of 1981. The date didn't go well and she decided, earlier than planned, to get the bus back to Belfast. She never made it and was found raped and strangled in a ditch in Kildare. All the forensic team had to go on were some pieces of thread, all roughly the same size and cleanly cut at either end, that were found in large amounts on her body. It was these loose ends that would provide the key to unravelling the case. There were so many of them that the forensic team concluded Deborah Robinson must have been already dead when they found their way on to her body. Finding out where the pieces of cotton came from would lead them to the scene of the crime - and, they hoped, the person or persons who killed her.
Almost immediately Gardai began taking samples of thread from every garment factory in the Kildare, Meath and Dublin area. Each sample was compared to the thread found on Deborah's body, and it took 11 months before a match turned up - from a factory off Arran Quay in Dublin. Blood samples were taken from all 12 men working at the factory to see which of them could have generated the semen found on the body of Deborah Robinson.
These days, with sophisticated DNA technology, scientists could tell exactly which one, if any, of the workers was responsible but in 1981 it was only possible to narrow the suspects down to three men. The three were investigated and out of this Richard O'Hara, a Belfast man, was eventually convicted of the crime.
O'Hara had seen the young woman standing at the bus stop and had come out of the factory to talk to her. He told her that he was driving to Belfast and asked her whether she wanted a lift. She agreed, and under the pretext of bringing her to his van he killed her, raped her and pushed her under one of the cutting tables in the factory, where she picked up the threads. Apart from this vital piece of forensic evidence there would have been nothing to connect Deborah Robinson with her killer.
When Mark Lawlor broke into the home of Rose Farrelly in Harold's Cross in Dublin three years ago, raping and brutally murdering the disabled elderly woman, he left plenty behind to connect him with his crime. Investigators were fortunate in this case that Lawlor provided a blood sample which matched the semen on the murdered woman's body. Ireland is one of the only jurisdictions in the world where a suspect is not obliged to provide blood for examination by scientists: this country is also unusual in that both the results and the samples must be destroyed after six months.
Also found at the scene were pieces of green suede, which were later found to have matched the material on Lawlor's trainers. During court proceedings the State's case was that before finding Rose Farrelly, Lawlor had been breaking into a number of cottages on the road.
In the house next door Gardai found a footprint on a bedspread which, when analysed in the forensic laboratory, was found to have been made by the right trainer of Mark Lawlor - who is now serving a life sentence for Rose Farrelly's murder.
When Marilyn Rynn was found raped and murdered after taking a shortcut to her home in Blanchardstown, Co Dublin, from a Christmas party in town, finding a match for the semen found on her body was crucial. It was 1996 and the mild, cool and dry weather at the time was to prove enormously helpful to the forensic team. Blood samples were taken from around 400 men, among them some who Gardai believed were prime suspects. DNA profiling allowed them to eliminate these, saving valuable time that would have been wasted on fruitless investigations.
One of them, David Lawler, did a bit of research before he decided to provide the forensics department with a blood sample. From the Internet he learned that semen would not last on a body for longer than six days. It had been 12 days before Marilyn Rynn's body was found, and he figured he would be safe.
But the Gardai had found traces of semen. Had it been raining, this evidence would probably have disappeared in less than six days. When Lawler was given the results of the test he confessed, and was subsequently sentenced to life for the murder and rape of Marilyn Rynn.
It is not only murders which tax the minds of the State's forensic experts; much of their work involves the search for fire accelerants when a suspected arson has taken place. It is their job to verify if a fire was started deliberately. The incident at the Bell View Hotel in Lisdoonvarna exactly 20 years ago provides a good case in point.
From the trail of evidence it was clear that the three men involved had spread petrol all over the bedrooms of the hotel, and then stood at the end of the last bedroom and struck a match. A ball of flame erupted, and one man was burned to death while the others were seriously injured. One of them was burned so badly that the flesh of his right hand came off, in Dr Donovan's words, "like a glove". It was found near a wall beside the hotel, along with other pieces of the man's flesh that had come away as he tried to make his escape.
A year later, when the flesh on his hand had grown back a Garda knocked on his door and asked to take his fingerprints. "You never know in forensic science when you will get some relevant piece of evidence," says Dr Donovan.
