Original subtitles

When a serious crime is committed and the police need all the help

they can get, there's one group

of people they turn to time after time, the expert witnesses...

Knowing when someone's done something is one thing, but proving

it's completely different.

We need that last piece of the jigsaw.

..an extraordinary army of men and women with the expertise

to reveal the hidden clues criminals have left behind.

It might be a fingerprint, footwear mark, cell site analysis,

that can come up with that golden ticket to put that investigation

on a different path.

Using the very latest techniques...

Several months or even years later, evidence can remain

and still be recovered.

..this is the inside story of how science helped solve some

of the UK's most complex cases.

The forensics in this case showed us what did happen, not

what could have happened, what did happen.

You've been in a scene, it's virtually impossible to clean

everything up. Something is going to be there.

If we're looking in the right place, we'll find it.

Without the unseen heroes painstakingly going through forensic

bits, I might not have got justice for my daughter.

This is the story of the expert witness.

In this programme, an expert witness examines a muddy crime scene

to determine how a body got there.

He was standing up, straight up, and he was just bent at the waist.

That in itself is interesting.

And when police investigate a number of complaints against a young man...

My gut instinct did say that there was something

up with him, something wrong.

But, unfortunately, I ignored my gut instinct and lived to regret that.

..a virologist is brought in to reveal if the suspect was guilty.

Where you have a transmission, you can see a resemblance

between the strains infecting the two parties,

and it was really that type of linkage that would substantiate

the allegations that were made.

Expert witnesses help investigations by seeing the clues the rest

of us can't.

When the body of an elderly farmer was found in a river,

it wasn't clear to detectives whether it was a case

of suicide or murder.

But a bio archaeologist was able to detect and decipher evidence left

at the crime scene.

Forensic bio archaeology can help criminal investigation

by interpreting the crime scene.

Sometimes the environment can give as much evidence as the body

itself, sometimes more.

June 2018, Gosmore in Hertfordshire.

69-year-old farmer Bill Taylor is reported missing from his home

by his family.

Reporting on the case for the national newspapers

at the time was Thomas Hornell.

Gosmore is a small hamlet and most of the farmland there was actually

owned by the Taylors. There was hundreds of acres.

Dozens of police ended up showing up and combing through every blade

of grass on Bill's farmland, searching for him.

So this was a really big police presence for a normally sleepy town.

Due to the sheer scale and complexity of the search,

the Hertfordshire Police Major Crime Unit were called in to organise

the hunt for Bill.

This was certainly the largest search that I've ever been involved

in and coordinated.

While search teams combed the countryside,

Detective Chief Inspector Carl Foster turned to Bill's

family and friends.

They revealed his personal life was complicated...

..estranged from his second wife,

Angela, and with his family at war.

Whilst Bill and Angela were separated,

they weren't yet divorced.

Angela wanted to get divorced.

Bill was effectively digging his heels in and saying,

"No, I don't want to do that."

Both Bill and Angela had children from previous marriages

and they had three children together.

And in particular, Bill's son from his first marriage did not get

on with Angela and her side of the family at all.

In fact, they completely loathed each other.

Bill was kind of stuck in the middle because Bill, obviously, loved both

sides of the family.

He had children and grandchildren in both sides of the family,

and he was stuck between a rock and a hard place.

Although police had no body with which to reveal a definitive

cause of death, they began to suspect foul play

from within the feuding family.

The police were suspicious of Angela because she didn't seem that moved

or distressed by Bill's disappearance, and detectives also

overheard her talking about him in the past tense.

However, detectives could not identify an obvious motive for why

Angela would have wanted her husband dead.

There was already a post-nuptial agreement in place between Bill

and Angela, where they'd already agreed on the allocation of property

and land worth anything from £150 million

to £200 million.

The title deeds had already been moved over to Angela as part

of that agreement, so that effectively, for me, said,

Well, there can't be a financial motive here, then.

But one discovery left detectives convinced someone in Bill's circle

held a serious grudge against him.

One of the issues that concerned us is the fact that his vehicle

have been subject to an arson attack the week prior to him going missing.

It had been attended by officers and a scene of crime officer.

The towel, the shirt and the fuel can that were found

in the Land Rover didn't belong to Bill.

We sent all of those off for forensic examination

to establish whether there was any forensic evidence

that would assist us.

Detectives continued their investigations, this time

into Angela's personal life, and identified someone

who raised their suspicions.

The police began to look at a man named Paul Cannon, who was a

digger driver who had done some work on Bill's farm

and was around a lot at Angela's place.

So they really began to look at those two,

suspecting a relationship.

Angela admitted she was having an affair with Paul Cannon,

and when lab results returned from the items in the burnt-out

Land Rover, they showed traces of Cannon's DNA -

significant, but not

enough to prove he was responsible for Bill's disappearance.

What the forensic evidence against Paul Cannon did was obviously

elevate our concerns around what was going on between him and Bill,

potentially Angela, and that whole family dynamic.

But on its own, does it explain what has then happened to Bill

a week later? No, it doesn't.

Nonetheless, Hertfordshire Police declared the case a murder inquiry.

Without a body, they didn't have enough evidence to charge either

Angela Taylor or Paul Cannon of any wrongdoing, but their investigation

was far from over.

We became aware that Paul Cannon had been employed at two quarry

sites, both within the county of Hertfordshire.

Whilst the two sites had been shut down,

if Bill has been murdered, could his body

have been secreted in either one of those quarries?

Any disused quarry is a hazardous environment.

These two were huge.

Concerned about the risk to police search teams.

Carl turned to bio archaeologist Jennifer Miller for advice.

I've a lot of experience with searching landfill for missing

persons and recovery of bodies buried within landfill,

so I was asked to advise what the logistics

would be for recovery of anything from this sort of environment.

We walked over the quarries, and they're both over an acre.

There's between 20 and 30m-high mounds of industrial waste.

And it's very, very unstable, very, very dangerous -

potential for collapse.

And it would have taken months, if not years, to search it all.

And without substantiated evidence to say that he was in there,

then it's not worth doing.

DCI Carl Foster took Jenny's advice and decided against excavating

the quarry.

Searching for more concrete evidence that Bill was murdered,

he examined mobile phones belonging to Paul Cannon and Angela Taylor.

They contained 28,000 text messages sent between the pair in the four

months before Bill's disappearance.

The contents were shocking.

So this is just a small extract from the thousands of messages

between Paul Cannon and Angela Taylor.

It starts with Paul Cannon,

"Got to get him out of the picture very soon, darling."

And she replies, "I don't know how to sort it. Someone else, maybe."

And Paul Cannon replies to the effect,

"I only know one man for that, and I haven't spoken to him

"in a long time, but I'll try."

The following day, the 17th of February,

"You phone that bloke, can't keep going on like this."

And Cannon replies, "I'm good, darling. Just spoke to man.

"Going to be about 20."

To which she replies, "I'll go halves with you."

Messages closer to the time of Bill's disappearance

were even more chilling.

26th of May was the night Bill's Land Rover was subject

to the arson attack.

And you've got a conversation here where Paul says, "Have to go

"to Dog Kennel, get something."

And Dog Kennel is the name of one of the farms that Angela owned.

Angela replies, "What you got to get?"

And then Paul Cannon replies, "Darling, you light my fire."

But both Paul Cannon and Angela Taylor refused to make any comments

on the significance of these text messages.

No comment.

Cos neither of you have said it to each other ever before.

No comment.

Bill was last seen alive around 9.30, by his grandson.

And then, some two hours later, Paul Cannon sends a message

to Angela Taylor saying, "Just watching Kill Bill 2,

"laugh out loud," which is pretty sinister when you know

the timeline and the sequence of events

and then you read that message.

The message is also contained

violent sexual fantasies centred around punishing Bill.

But, tellingly, they all stopped the day Bill disappeared.

The recovery of these messages was a huge leap forward

in the investigation.

I would describe those messages as a black-and-white transcript

of a conspiracy to murder Bill.

Angela Taylor and Paul Cannon were both charged with murder.

But Bill's body was yet to be found.

The case against the pair was far from watertight.

We were preparing for a no-body trial.

The defence would exploit that and suggest that he's

potentially taken himself off.

He might have a girlfriend somewhere. He's done, he's had

enough, and he's walked out of his life.

Then, in February 2019, eight months after Bill Taylor disappeared,

a chance discovery gave detectives a massive breakthrough.

Bill's remains were found by a fisherman who wanted to get

the perfect spot, so he'd actually gone onto private land owned

by Angela and discovered the remains of Bill Taylor by the river bank.

The body offered detectives an entirely new set of clues,

which could reveal for the first time how Bill Taylor died.

We knew we were going to need to demonstrate that Bill hadn't gone

there to take his own life, and he hadn't gone there

and been victim of some form of medical episode or accident.

DCI Carl Foster needed a thorough forensic analysis of the body

and the river bank where it was found.

So he turned again to expert witness Jennifer Miller.

My remit was primarily to recover the body and interpret events

at the scene,

so how the body had got into the river, as best as possible.

The mud was just short of a metre-deep.

All you could see was a head just at the banking, and the back,

which was covered in algae and there was nothing else visible.

So it was face-down in the mud.

The first thing to do is try to understand how the body is lying,

so the disposition of the remains, as it's called.

And we were able to identify quite quickly that although he was lying

face-down, he was actually standing up and he was just bent

at the waist, so that in itself is interesting.

It's an unusual way to be in.

This unusual position made Jennifer doubt that Bill had become stuck

in the deep mud on his own.

The positioning of the body was such that both feet were facing the bank.

It would be very difficult to walk in backwards through that thick mud

without losing your balance and falling backwards

rather than forwards, and perhaps that's the key point.

As you lift your leg to go forwards, you're more likely to overbalance

backwards than you are forwards.

It's more suggestive of being laid there, being put over somebody's

shoulder and with the feet facing forwards and deposited.

What's more, Jennifer concluded Bill may well have already been dead

by the time he was placed in the river.

I think it's unlikely that he was put in there alive and effectively

kicking because he didn't kick,

the feet were together, the knees were together,

his thighs were together, he was bolt upright.

And it's very unlikely, in my opinion, that he was conscious

when this happened.

Under Jennifer's supervision, Bill's body was carefully recovered

from the mud and sent for postmortem. That revealed injuries

to his neck consistent with strangulation.

The case against Angela Taylor and Paul Cannon was now as strong

as it could be.

Their trial began in September 2019, and Jennifer's evidence was crucial.

At the trial, the defence were quite robust in their questioning.

They insisted that he had potentially walked in and asked me

to say if this was possible, and I did explain to them

that having never taken a body into the mire, I don't know,

but I'm quite convinced

in my own opinion that had he walked

into the mire, then the disposition

of the remains would have been very different.

Jen was really important around the interpretation

of that deposition site, her evidence was absolutely solid,

and, yeah, couldn't ask for more, really.

They talked of torturing him in text messages, discussed the cost

of hiring a hit man,

and today they were found guilty of his murder.

A jury has decided that wealthy farmer Bill Taylor was killed

by his wife and her lover for refusing her a divorce.

REPORTER: Duplicitous and calculating and plainly besotted,

that was the judge's assessment today of lovers Angela Taylor

and Paul Cannon as they were each sentenced to 21 years in prison

for the murder of William Taylor.

What a pointless, pointless exercise.

The old-fashioned just removing a love rival, but it just seemed

so unnecessary to murder

an old man who is causing them

no problem whatsoever.

Yeah, a real shame.

However unusual the crime, there's a science that can help solve it.

In this next case, dozens of victims and a national manhunt led police

to the suspect in a one-of-a-kind criminal investigation.

But in order to secure a conviction, police needed the expertise

of a virologist, an expert in viruses.

My main interest has been in the field of the evolution

of viruses, how they change over time.

And I think that's obviously something that we're all very aware

of with the Covid pandemic.

Edinburgh 2015, where a shocking crime is unfolding, one

that will span the UK, affect dozens of gay men and end

in a dramatic national manhunt.

It started with one man, 26-year-old Daryll Rowe,

and one of his victims, Stuart Rodger.

I came across Daryll Rowe through an app called Grindr,

which is a sort of dating hook-up app, a bit akin to Tinder.

I agreed to meet with Daryll,

and during that encounter he appeared

to tamper or sabotage the condom which I had insisted on being used.

And at the time I just wrote it off as me over-worrying about something.

I kind of felt quite grotty after the encounter with Daryll,

and, you know, the truth was there was a very dark

atmosphere around him, which was unmistakable.

My gut instinct did say that there was something up with him

and that there was something wrong.

But, unfortunately, I ignored my gut instinct and lived to regret that.

Stuart's instinct that something was wrong was confirmed within days

when he received a string of sinister text messages from Rowe.

About eight days later

after the encounter, he sent me a series of abusive messages

revealing to me that he had indeed sabotaged the condom,

along with a series of other insults and taunts.

I felt an enormous sense of alarm and disturbance when I got

those messages, and I knew that because he'd sabotaged a condom,

I was at risk of contracting something,

so I arranged am HIV test as soon as I possibly could.

A couple of weeks after that, I got the phone call

from the clinic asking me to come in that day and telling me

that I was HIV-positive, and I knew it was definitely him.

I did contact the police, I think, within about a week of my diagnosis.

You know, I was determined to get justice and I gave a full

statement about what had happened, told them

that this man had violated my consent and showed them

the screengrabs of the messages that he had sent me.

Police Scotland moved to arrest Daryll Rowe, but he had fled.

Detectives searched for him and were astonished when he turned

up 500 miles away in Brighton.

Here, he was deliberately infecting more men with HIV.

BBC journalist Carol Erskine reported on the case.

In Brighton, another one of his victims had found out

he had tested positive for HIV.

He had gone to a clinic to be tested, and while he was there,

he had shown text messages that Daryll Rowe had sent him,

these terrible, horrible messages

that he had sent him, to staff at the clinic.

And they then realised that they had seen other men

in the clinic who'd had similar messages.

Police now suspected they were dealing with a serial offender

who had left behind 14 victims in Edinburgh

and now eight new victims in Brighton.

Sussex Police caught up with Daryll Rowe and he was arrested

on a charge of GBH.

But Rowe denied all the charges, and under questioning, he claimed

he was not even HIV-positive.

Do you have HIV? No.

Have you had a HIV test recently?

Erm, not recently.

I had a relationship when I first got here and it was unprotected,

so I've not been tested after that.

OK. So what you're saying is a

couple of months ago you had a relationship, had unprotected sex.

When I first got here, I was dating somebody pretty quickly,

and it got quite intense.

Daryll Rowe was bailed in Brighton to return to his foster

parents in Scotland.

It was after three weeks of living with them that he went on the run

and was missing.

Detectives were convinced Rowe would offend again.

They shared his image with the media and a national manhunt

swung into action.

Police found his tent in the Pentland Hills and they were able

to identify it as being his because it had his medication inside.

But for months there was no sign of Rowe until one man saw Rowe's

image and had a chilling realisation.

He was living in Newcastle with a man who believed

he was in a relationship with him and had no idea

of his previous history.

Rowe had changed his name and bank details, but continued

with his prolific crime spree, infecting even

more victims with HIV.

The nationwide manhunt to find him uncovered further victims,

and he was actually discovered on a dating website when police

were able to compare pictures of his genitalia and discover

that this is the man that they were looking for.

After a joint operation by Northumbria, Scotland

and Sussex police forces, Rowe was finally arrested

in North Tyneside.

But he claimed that his accusers could have caught HIV from anyone.

Detectives needed to prove that the infection could only

have come from Rowe.

So they turned to an expert witness, Peter Simmonds,

Professor of Virology at the University of Oxford.

We were provided with blood samples from Rowe and several alleged

victims of him.

We separated white cells from those. Within the white cells,

there'll be copies of HIV,

often very low numbers.

But we will then amplify those up to an extent, which means

we can then directly determine their genetic sequence and analyse

them for linkage.

HIV evolves very quickly.

So it's not just one strain,

there are literally hundreds of thousands of different strains.

Where you have a transmission of HIV,

then you can see a resemblance between the strains infecting

the two parties.

And it was really that type of linkage that we're looking

for to substantiate the allegations that were made.

We conduct what we call phylogenetic analysis that will show

whether these strains cluster together

or whether they're unrelated to each other.

Well, if we find a strong clustering of strains and in fact, in this case

we did, what this shows, effectively,

is they share a similar or common

strain of HIV, and that would generally be acquired

through transmission between them.

Having concluded a strain of HIV was common among Rowe

and his victims,

Professor Simmonds now had to recheck his results

and run the analysis a second time.

We were provided with a second set of samples, and the idea of

that was to show that we reproducibly got the same

strains from the individuals in a different set of samples.

That was actually what the defence expert would demand

that we provide as evidence.

In 2018, Daryll Rowe was tried at courts in both

England and Scotland.

He was charged with causing grievous bodily harm with intent

to infect HIV.

He became the first man in the country to be found guilty

of intentionally trying to spread the virus.

When we were in court, I saw him in the flesh for the first time

since the incident, and that was very nerve-racking.

It was kind of a vindication to see him,

to kind of see him kind of cut down to size,

and he was a much more belittled

and humble figure sitting there in the dock.

I went to court and had to testify to the judge and jury.

Finding such a strong cluster in such a large number of people

was actually key to the certainty that Rowe was involved in this,

and I think the genetic evidence was very well understood by the jury

and probably influenced their decision that he was guilty.

Rowe was sentenced to 12 years in England, and in Scotland

he was given eight years and placed on the Sex Offenders Register.

I felt a huge amount of relief, most of all.

Sadly, a lot of victims of sexual violence don't get justice,

and I was very lucky in that respect.

And actually, that's a credit to the professionalism of everybody

involved on the case.

Peter Simmonds' work was crucial in convicting Daryll

because it helped us get to the point where it could be proved

beyond reasonable doubt that it had been transmitted

from him to me.

Without virology findings, the prosecution would rely

on the fact that there was a consistent contact history

between Rowe and the individuals concerned.

So having the genetic evidence was certainly very important in showing

the linkage between HIV strains within the various parties involved.

Two very different cases there, but both needing the extraordinary

skills of expert witnesses to dig beneath the surface and help

detectives uncover the truth and bring those responsible

to justice.