Body of evidence: meet the experts working in crime scene forensics

I was in the military before I started in forensics. I was a communications engineer in the army. Someone suggested I look into digital forensics. I was a bit of a sceptic at first, but I didn't understand what could be done. I have worked in both the private and public sectors, and I am an independent expert.

Everything I do starts with a phone or computer. I will be given the device when I prosecute or defend, or all the data once it has been obtained. I want everything I can get my hands on. I am looking at all sorts of information, from the content of messages to locations. There are call logs, emails, pictures and more. It is rare for a case to not have digital evidence in play, from terrorism to violent crime to missing persons.

It is rare for a case not to have digital evidence.

Data which might be useful can be deleted. When it is legal and authorities have the right to do so, my job is to identify what is hidden, starting with backups on the device or online. Information is kept after a user has removed it. The system logs and communication logs will be there after the original image has been put in the bin.

Texts and calls were once done by phones. It is unrecognisable compared to what they do now. We have good tools, but we are constantly playing catchup with the criminal world. The problem is that even the most basic technology can be used by criminals to their advantage. Much of the information I can get from my mobile devices comes from the internet. Global criminal networks can avoid this by logging into an email account online, writing a message and leaving it in the drafts folder. Someone else can sign in, read and respond without leaving a trace. I have to work harder with the data spread across different places.

I am careful about how I use my phone and apps, but I think that is related to the age. I didn't share my life online until I was 60. It would seem odd to start my work.

Rosie is a forensic ecologist.

Rosie Everett said there was endless information in the shoe. The Observer has a photograph of Levon Biss.

I am sitting at the interface between archaeology and forensics. I am an environmental archaeologist who uses minuscule materials found in the natural world as clues, whether to try and solve crimes, or to imagine what landscapes looked like thousands of years ago. Microfossils are invisible to the naked eye. I turn to the tiny, single cellalgae that grow in wet conditions from soils to the ocean. Examining them closely at crime scenes and on evidence can help paint a picture.

What is it like when you start a case with soil? Is it unique? Which animals are living inside? There will be many variations, from Scottish highland mulch to urban grit. Can the diatoms be traced on the suspect's clothing, personal possessions or a car that was used in the crime? There is a lot of information in the shoe.

Examining cells at crime scenes helps paint a picture.

These techniques are usually used to solve violent crimes. I am also working on heritage crime. Illegal excavations of important archeological sites are a real problem. Much of our history can disappear with little enforcement. That is where forensic ecology can help.

I had a case last year about Beeston Castle. In December of last year, five men took off with axe heads and other bronze age artifacts. The police got involved after attempts were made to sell the items. The suspects simply claimed they found the haul elsewhere. I took soil samples from the castle and created a profile. I found a direct match within the axe heads. Securing convictions from this type of crime is incredibly difficult, but using our techniques, the men were found guilty.

My field is not well known. It is difficult to take evidence to court in a way that both the judge and jury can understand. People usually understand the basics of fingerprints and DNA from books or shows. Diatoms? Most people don't have a clue. Silent Witness has a forensic ecologist in it. She is based on me.

Dr Amoret Whitaker is a forensic entomologist.

Amoret Whitaker, forensic entomologist, said, "Up close you see how fascinating insects are." The Observer has a photograph of Levon Biss.

I always thought I would end up working with big, cute and furry animals. I dedicated my career to the study of flies and fleas. I knew I would use a microscope for the first time. Most of us don't see them in their full glory, but up close you can see how beautiful and fascinating they are.

My PhD was about the decomposition of flesh and what the insects on bodies tell us. The Anthropological Research Facility is also known as the Body Farm. I was called out to do casework before I finished writing my research. I teach forensic investigation as well.

I can estimate the time of death by studying flies.

Blow flies are my focus in forensic work, the little creatures most of us only ever spend time swatting. They can give many answers in my line of work. Blow flies are the first to arrive after death. Eggs will hatch into tiny larvae. Other insects will show up. The minimum amount of time since someone died can be determined byciphering each stage.

I can estimate a time of death within a few hours, and I can help rule out periods when the death couldn't have happened. This helps detectives focus their investigations, calling on all sorts of evidence relevant to that specific time. That is a lot to learn from a fly.

This path seemed interesting to me. I wouldn't have believed them if they had told me this would be my career when I was a child. I want to find the truth and not put people behind bars. My evidence can result in convictions, but what I find may also indicate innocence. I remain neutral. I can not support a single theory. I will write an analysis, write a report, and see what comes out.

Sometimes I get affected by what I see. The music on the radio is very loud and the air hits my face with the windows open. It makes me feel alive.

Dr Emily Chiang is a forensic linguist.

Emily Chiang, forensic linguistics, said that there was a person on the dark web who was partially identified because he used an unusual greeting. The Observer has a photo of Fabio De Paola.

Improving the delivery of justice through language is a tenet of forensic linguistics. We will look at any criminal or legal context where language is an issue. Language barriers in the justice system need to be highlighted. It also means catching the bad guys.

We try to determine who wrote a particular piece of text. A forensic linguist will compare the relevant evidence with known writings of potential suspects. Our job is to find out who was responsible for writing it.

A basket of potentially useful features is one of the characteristics we look for. It could be odd spellings and phrases. Where you would say "hello" is where I might say "hi". The dark web has an individual who uses the greeting "hiyas" regularly. All uses of language are the same. We call the choices we make the "idiolectal choices" because they are often subconscious. I want to find the patterns these habits can create in order to identify the author.

Patterns in language and writing are what I look for.

We try to describe the type of person who might have written something based on these decisions. There are markers for gender, socio-economic and professional issues. We look at the ways in which other languages influence us. This can be very valuable intelligence when attempts at extortion are made.

dictionaries to help juries interpret the meaning of messages later presented as evidence are becoming more and more common. This can be used to prove intent or conspiracy to commit a crime.

The internet presents a whole new arena for us, with potentially vast applications, but forensic linguistics has been around since the 1970s. It is impossible to hide your language online, and anonymity is a real challenge to law enforcement.

We train law enforcement officers who might need to go undercover online, so they are equipped with the relevant language to sound plausible. This could allow them to catch abusers by knowing the relevant lexicon. An officer might need to jump on to a victim's device to catch an offenders. Helping them communicate is important in the account takeover scenarios.

Criminals will catch on. Gloves can be used to hide fingerprints, and similar attempts will be made online. These efforts at subterfuge could create their own distinctive patterns for us to identify and analyse. It is part of the job.

The final series of Line of Duty was about forensic linguistics. There was a certain word that was misspelt. The exposure made us angry. There was a high chance that certain messages had been sent by a specific suspect. We wouldn't claim to be so certain in real life.

Dr. Miranda is a tattoo forensics expert.

I am interested in everything from the chemical makeup of inks to what can be drawn out from a tattoo's imagery, says tattoo forensics expert, Michelle Miranda. Benedict Evans is the photographer for The Observer.

I am a forensic scientist for most of the time. I have taken the crime scene to courtroom approach for most of my career. It is a necessity when you work in an NYPD crime lab. You have to use all the traces at your disposal, from fingerprints to the analysis of gunshot residue.

I went back to school to get my doctorate because I wanted more from my work. I continued to work as a medical photographer and investigator after leaving the police. I contemplated a career change into art preservation. I wanted to explore my own area. There was a case that changed the course of my career while I was working on death scenes. The only way we could identify the woman was by her tattoo, which was a rose with her name on it. This evidence was used to identify the victim. They secured a conviction for the man who killed her.

Where the body art was done is revealed by the ink used in the tattoo.

Before I started my research, few people had considered tattoos in forensics as a means of identification, and in other ways as well. I am interested in everything from the makeup of ink to what can be seen from a tattoo. The field is still in its infancy and I am still assessing the significance of what can be done. I'm interested in looking at the ink itself. If a tattoo can be seen, could it tell us when the body art was done? We have techniques to look at tattoos that have become damaged.

The biggest problem I have is that people in the field don't know I exist. They may not even consider tattoos. I would like to see tattoos considered a key part of investigations. I would like to be that person called to the scene.

Mark Spencer is a forensic botanist.

Mark Spencer said that you can't know if you'll be able to emotionally and physiologically deal with the experience until you get there. The Observer

My interest in plants was before my memory. As soon as I was old enough to crawl, my mother says I would sit and stare at vegetation. Plants have always been my favorite thing. I was reading degree level textbooks on botany when I was 10 years old.

After completing my PhD, I worked as a habitat surveyor, recording the flora and fauna of London. The Natural History Museum was where I became a curator. I got a phone call one day that said, "We've got a dead body in a ditch, can you give us a hand?"

I jumped into the train at the deep end. You just learn on the job. You don't know if you'll be able to deal with the experience until you get there. I found I could.

I help the police find missing bodies.

I help the police search for missing people. Sometimes these are cold cases, where someone has been in situ for a long time. I want to know where a body might be in the natural environment. When a body is discovered, I help identify how long the person has been dead. The plant life could hold clues as to whether there was a struggle or not. The vegetation around the body is full of clues. I look for trace evidence that could link a suspect to a crime scene. I would make an inventory of all the plants in the area if there was a body. I will look at the plant life that might link the two if there is a suspect.

People don't see vegetation as having a story to tell, but just as green. I can look at two bushes and draw out different details. One might be decades old and the other rapidly grown. I can tell if it has been left to grow or if it has been hacked away. These observations can prove very important.

You work until you drop when you get called into a crime scene. It is not just the mental efforts that tire me out, but crawling through the mud while it pours with rain. I am in my 50s and my knees can hurt. I worked 70 hours in six days on my last case. I barely spoke or moved when I got home. How do I relax? A zombie film and a glass of wine.

Mark A Spencer wrote a book about a forensic botanist called Murder Most Florid.