A day in the life of senior forensic biologist Charles Connor is typically spent in the lab.
An authorised crime scene examiner, biological examiner and DNA scientist at Forensic Science Service Tasmania, Dr Connor also attends major crime scenes to work hand-in-hand with Tasmania Police by providing expertise such as bloodstain pattern analysis and scientific testing.
"We are very much lab-based. Generally, we get called up to the major crime scenes - murders, sexual assaults, major woundings," Dr Connor said.
"Police will deal with minor crimes such as stolen vehicles or house burglaries without us."
FSST has one lab based in the South of Tasmania which services the whole state.
The team consists of 32 staff - 17 in the biology section, nine in the chemistry section, five administrative staff and one director.
With a medical research background, including Honours in microbiology and virology and a PhD in medicine, Dr Connor began working at FSST in 2002 and now performs a number of roles at the service's lab.
He said the biology section at FSST usually received about 3000 case files a year and, with some cases having multiple items, the section received about 7000 items for examination.
His day generally starts off with receiving a file before he heads into the lab to examine an item.
"We do have a little bit of context as to what might have happened, what's alleged to have happened," Dr Connor said.
"Then, to some extent, we examine the item based around that information.
"I examine items on a clean bench then applying specific tests to that item I take samples for DNA profiling."
What is DNA profiling?
DNA, which stands for deoxyribonucleic acid, is found inside almost every cell in a person's body.
It is unique to individuals and therefore an effective tool for law enforcement and identification purposes.
To make biological samples, such as blood or semen, into a format where DNA in the samples can be compared between people, the samples must undergo a multi-step process called DNA profiling by a scientist like Dr Connor.
"As a DNA scientist my role is to extract DNA from any samples that are taken from the crime scene items," Dr Connor said.
"The first step is really to break open any cellular material that might be present in the sample to release the DNA into a solution.
"Then we purify any DNA that might be present.
"We are left with a small amount of DNA, potentially, from a sample and what we want to do is make lots and lots of copies of specific areas of that DNA that are unique to individuals."
Dr Connor said this information was then converted into letters and numbers to allow it to be compared to other DNA profiles through a computer database.
"The output of the instrument that we use is a graph with peaks called an electropherogram. We convert those peak positions into a series of letters and numbers," he said.
"That's what a DNA profile is and that's what's uploaded onto our searching database."
Finding a match
Dr Connor said once DNA from a sample had been profiled it was then a matter of comparing that crime scene profile to a reference sample from a known person.
"If the two DNA profiles are exactly the same we call that a DNA match. If they are different basically we can exclude that person as being the source of that DNA," he said.
Dr Connor said he looks for 21 different regions of the DNA molecule.
"We know that each of those areas we look at vary within the population from one person to the next, such that the chance of two people having the same DNA profile if they are unrelated is less than one in 100 billion," Dr Connor said.
"Sometimes we get partial DNA profiles when we don't get a result at each of the 21 locations.
"We can still make a DNA match from that, it's just the chance of someone else having that profile is higher."
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He said samples from crime scenes could have what is called a mixed DNA profile which contains the DNA of two or more people.
"We have a particular statistical calculation that we apply to that which looks at the likelihood ratio of one person being a contributor to the DNA profile compared with another person in the population also being a contributor," he said.
Dr Connor said DNA matches could also be found by running the profile through a computer database.
He said he used two databases, one local and one national.
"On our local DNA database we've got about 27,000 unique reference samples that are profiles from the Tasmanian population," he said.
"We're up to nearly a million, just over 980,000, on the national database.
"There are lots of different categories but our main categories are suspects, serious offenders, victims, volunteers and then, of course, crime scene profiles."
DNA 'crucial' in solving crimes
Dr Connor said in cases where there was an unknown offender DNA has proven to be very important.
"Sometimes it's crucial," he said.
"Other times it's really used just as intelligence information to back up a witness statement or to assist the investigation as it goes on."
He said an example of where DNA had been pivotal was a 2005 case where an elderly lady in Devonport had been sexually assaulted.
"Her eyesight was quite poor. She thought the offender was actually her gardener," Dr Connor said.
"We managed to get DNA profiles from the crime scene which didn't match the DNA profile of the gardener.
"It was a process of then trying to run through a number of different suspects and we were actually able to exclude the gardener but also find the offender that way."
Dr Connor said DNA also led to the identification of a person who had sexually assaulted a young woman on a running track at Cornelian Bay in Hobart in 2012.
"We ran the DNA profiles from the crime scene and matched it to an individual who was on the DNA database who was at the time unknown to police for being involved with this sexual assault," he said.
Another prominent case where DNA was pivotal was the widely reported 2015 sexual assault of a 76-year-old woman in Launceston.
"The reason [the offender] was found to be a suspect and subsequently has been prosecuted for this is that we found DNA matching his profile on the victim's nightie," Dr Connor said.
"In all three cases, they were all unknown offenders at the time.
"We were able to run them through the system quite fast because they became priority cases and we were able to get DNA matches to provide to police."
Having worked as a forensic scientist for 18 years, Dr Connor said he had seen a lot of improvement in DNA profiling and biological examination techniques.
"In DNA profiling, we've gone from tests that aren't necessarily very powerful for identifying individuals to now a test that's very powerful and very useful for making identifications," Dr Connor said.
"We did have a test that gave us a statistical result of the chance of someone else matching that profile being in the millions now we are certainly in the septillions.
"By default we report it as the one in 100 billion chance of someone else matching that profile.
"In biological examination, the tests have become more sensitive, more reliable and more robust."
Dr Connor said the best part of his job was working on coronial identification cases.
"The reason I really enjoy those is because you are able to make an identification of a deceased and that deceased person can be repatriated back to their family for a funeral, for burial or for cremation," Dr Connor said.
"I find that really satisfying that I can actually help the family directly that way and provide some closure."
Similarly, Dr Connor said he also enjoyed his work as a specialist in disaster victim identification.
"When we have a major fatality [like a fire or flood] ... disaster victim identification involves going out into the field and collecting human remains and property belonging to those human remains and trying to repatriate those back to the families for burial," he said.
"Once an event like that has happened and there's deemed to be multiple fatalities and they can't be identified by visual, or dental or fingerprints then DNA becomes really important as one of the primary identifiers for the coroner."