The investigators

Transport Accident Investigation Commission air investigator Ian McClelland.
Transport Accident Investigation Commission air investigator Ian McClelland.

Where the uninitiated see only mangled metal, scorched earth, or flesh alive with insects, they see clues. Nikki Macdonald meets the investigators who piece together events from scant remains.

When his phone rang shortly after 8am on January 7 last year, Ian McClelland was on holiday in Akaroa. By early afternoon he was pacing a Carterton field strewn with the remains of 11 lives and a rainbow- coloured balloon. His task: to reconstruct that fateful flight from the charred remnants of fabric, wicker and steel. To find out what went wrong, and why.

To the public it was one of New Zealand's worst air disasters. To the veteran of more than 60 air accident and incident investigations, it was another day at the office.

Ian McClelland – amid the debris of last year’s fatal Wairarapa hot air balloon crash – is the air
accident investigator who had to figure out what went wrong and why.
Ian McClelland – amid the debris of last year’s fatal Wairarapa hot air balloon crash – is the air accident investigator who had to figure out what went wrong and why.

An "old and crusty" air force pilot of 22 years, McClelland joined the Transport Accident Investigation Commission (TAIC) 16 years ago as an air accident investigator. He's plotted events leading to downed planes, downed helicopters, near misses.

On 4 September, 2010, when the 7.1 magnitude earthquake rattled his home town of Christchurch, his boss told him to take Monday off to clean up. Hours later he was flying to Fox Glacier to lead the inquiry into the death of nine people in a skydiving plane crash, leaving his family behind with no power or water.

The reward, McClelland says, is giving the victims' families some sense of closure. For the families of the 11 balloon crash victims that process finally ended this week, with the release of the accident report, after 21 months of investigation.

For five days McClelland combed that Carterton field alongside police and his team of three, working his way slowly in towards the blackened scar. He examined the 11,000V power lines witnesses said the balloon touched. He checked weather stations, read witness statements gathered by police, scrutinised photographs.

He put aside emotion and tried to account for "what's there, what's not there, what's there that shouldn't be there". But most of all, he resisted speculating.

"Too many people say 'Oh, well, it's obviously hit the wires and that's the problem' - well, maybe there's something else to it. You're not doing any analysis until you've got all the evidence you possibly can."

As the ringbinders of evidence accumulated, McClelland mentally classified clues into "hard evidence" and "volatile evidence". Among the volatile evidence is human memory.

There were numerous eye witness accounts of the Carterton disaster, from the trip photographer - who captured the moment the balloon struck the power line - to the crew chief who heard balloon pilot Lance Hopping yell "duck down", to a nearby resident who saw passengers trying to push a second wire off the basket's lip, to the farmers and cyclists who saw the balloon erupt into flames and drop 150m out of the sky.

But memory can play tricks: witnesses can be adamant of their recollection even when physical evidence excludes it. And memory is malleable. "Stories change quite a lot . . . The trauma can affect a lot of people, and also people's experience. One of the worst witnesses is a pilot, because they will try to interpret what they see. The best witness is probably someone in the 10-15 age bracket who doesn't watch too many movies and isn't going to jump to conclusions. They just tell you what they see."

TAIC reports can't be used in court, except at a coroner's inquest, to encourage those potentially at fault to tell the truth without fear of prosecution. But that doesn't make their evidence any more reliable.

A balloon maintenance engineer originally told investigators he tested the balloon fabric with his hands, rather than using the approved spring-gauge strength test. In a second interview he said he used the proper test when required and later still he claimed he used the correct test "at all times".

At TAIC's secure Wellington storage warehouse, what's left of the balloon's 25m high, 6000 cubic metre canopy is bundled in a corner, behind "Danger Keep Out" tape. By the wall is the bent frame of the balloon's burner. In front is the balloon basket, almost bare of wicker, its steel framework intact but misshapen. Everything is blackened - sooty footprints walk the cold concrete floor.

McClelland pulls on overalls and gloves and takes a gas bottle from the basket end where Hopping would have stood. At the crash site, the four fuel bottles were scattered, their bases stoved in from the fall. But they were replaced in the basket when the wreckage was lifted carefully on to wooden boards and sent back to Wellington.

This is McClelland's hard evidence. In the bottle's base is a tiny 2mm puncture hole caused by electrical arcing from the power cable. The resulting blast of gas under pressure fed the fire that eventually engulfed the canopy, sending the balloon plummeting to the ground.

McClelland picks up a section of the high-tension wire looped on the floor. The ends are frayed like unravelled rope but there's no obvious damage. He points out a smudge where the strands are slightly fused, barely visible to the untrained eye - more evidence of arcing.

He might have 22 years' flying experience, but McClelland's never piloted a balloon, he's not a linesman and he's not an expert on the body's ability to break down cannabis, which showed up in Hopping's system in an autopsy.

But he has to grapple with all those details, with the help of advisers, ranging from fire service and power board specialists, to toxicologists and the Air Accidents Investigation Branch in Britain, where the balloon was made.

After site evidence comes the question of "man, machine and environment" - trawling pilot records, boxes of aircraft- maintenance files, weather reports.

Combining the physical evidence, trip photographs, images recovered from a passenger's camera, witness reports and data from the pilot's damaged GPS, McClelland plotted the balloon's flight path and recorded what happened. But there were no eureka explanations, and seldom are.

And the investigations are only the beginning.

Then the commission takes over, cross-examining the investigators in the courtroom-like commission room and delving further into issues, including cannabis toxicology in this case.

Even after 21 months of deliberation questions remain. The best closure families can hope for is that the industry hears the commission's calls for change.

The bug woman

The sour smell of a fetid rubbish bag seeps from the open sample jar. Hardly surprising given its contents - mince and maggots grown for our visit.

That, says bug woman Julia Kasper, is nothing compared with the stench of a corpse infested with fly larvae, or the pigs she used to bury in backyard experiments. But rather than running from the olfactory monsters born of decaying flesh, Kasper is trying to better understand the odour chemicals in the hope they could provide more accurate estimates of time of death.

When she's not working her day job, as a Te Papa collections officer, the Hamburg-trained entomologist works on the project that's consumed her energies for more than a decade, culminating, but not ending, with completing her PhD in July. It's seen her suck insects from a badger carcass through a tube (not recommended), scavenge mesh frames from skips to keep predators off her backyard experiments, and examine the scuttle flies infesting a clingfilm-cocooned corpse found under the bed of a Hamburg man who'd shot himself. It turned out to be his wife, reported missing a year earlier.

"You don't think about 'there is a person', you have to deal with that later. You want to know what happened. I actually see the maggots and the flies and the eggs more than the corpse."

Forensic entomology - the science of using the insects that settle and develop on a corpse to estimate time of death - dates back as far as 13th century China, but has come into its own since the 1980s.

Forensic entomologists have also been known to transform suspected suicides into murder inquiries by identifying maggots in unlikely places. Flies usually lay eggs in natural orifices to allow easy access to soft tissue, and the hard skin of the hands is among the last to be colonised. So if maggots have infested the palms early in the decomposition process they've probably been laid into wounds, suggesting hands raised in self defence.

Kasper moved to New Zealand four years ago. The 40-year-old started investigating cases here when the body of pensioner Michael Clarke was discovered in a council flat in 2011, having lain there unnoticed for up to 14 months. She has worked on six Kiwi cases so far.

If possible, she'll visit the crime scene, to see how the body is lying and check humidity and temperature - all factors that can affect the time flies take to develop.

She'll tweezer out eggs, or maggots, preserving half in alcohol and collecting half alive, to be measured and bred to maturity to help identify their species and stage of development.

Flies take 1-2 weeks to mature. Different species colonise at different times - green bottle blowflies can arrive within four minutes of death, whereas scuttle flies and cheeseskippers prefer drier mummified tissue later in decomposition, and beetles can feed off both fly larvae and decaying flesh.

Using vast databases plotting development of different species, Kasper can estimate how long the person has been dead by the species present, and their stage of development. What she can't determine is how long the body was there before the insects arrived, meaning any estimate can only calculate the shortest possible time since death.

The purpose of her PhD project has been to determine which odour chemicals are released at which stages of decomposition, and which of those chemicals are attractive to which insects. The idea being that you can work out the time between the person dying and flies arriving and laying eggs if you know which odours the egg- laden female is attracted to, and how long after death those chemicals are produced.

To test her theory, Kasper decomposed mice at different temperatures and humidities and analysed the stench emitted at six distinct decomposition stages. She identified 51 compounds and showed that different odours were emitted at the various decomposition stages.

She took that further, placing a decaying mouse into one of four olfactometer chambers over which a fly could then walk. She assessed the fly's attraction to the putrid odour by the amount of time it spent patrolling over the mouse chamber. What she proved was that different fly stages were attracted to different degrees of decomposition, and that it's vital that entomologists differentiate between male flies and mated female flies when documenting their arrival on an experimental carcass, as they're attracted to different odour compounds and behave differently.

Kasper hopes her research will help improve the accuracy of time of death prediction.

The forensic pathologist

It's been a rough week for forensic pathologist John Rutherford. Eleven autopsies, eight of them suicides.

Even after two decades in the job he can't fail to be moved by the sad stories of those who land on his mortuary table. But once the white gumboots go on there's no room for sentiment.

"I don't think I could be described as one of these vulture-like people who want to stick their knife into you and dissect you. I think the human body is something to be respected, as is the human mind. But I think that thing that comprises the human being has gone. We are dealing with the casing, the shell of whatever was there before."

The 65-year-old moved here in 2006 from Britain, where his work included dissecting the exhumed bodies of victims of the notorious Dr Death, Harold Shipman. He's already featured in several high-profile New Zealand cases, including last year's Scott Guy murder trial. He also worked on the Carterton balloon crash, conducting three of the 11 autopsies and spending two days at the site, helping in the grim task of identifying human tissue among the charred debris.

You'll have seen him on television, unmistakable for his plume of snowy hair and the clear speech of a deliberative thinker. He's a man who never got around to becoming a psychiatrist because he figured he needed to be educated at the university of life, and then specialise in neurology, before he could truly understand people's problems.

It's 2pm and Rutherford has already done one autopsy - "a chap with a bad heart who collapsed and died after an altercation with his wife". It's one of about 245 he'll undertake in a year, of which only about 33 are suspicious deaths.

Often the suspicious ones are among the most straightforward. It's not hard to decide how someone died if they have a bullet hole in their head or multiple stab wounds. The tricky cases are those like that morning's, or last September's death from a heart attack of drug dealer Michael Mulholland, 16 to 22 minutes after a thumping by two Mongrel Mob members - the cases where Rutherford must disentangle the contributing threads of trauma and pre-existing disease, and apportion blame. In the case of the balloon crash, that meant trying to deduce from the limited evidence that survived the fire the relative roles of smoke inhalation, injuries from the balloon's rapid descent and direct burns.

An average autopsy takes one to two hours "from knife touching skin to starting to sew up". It takes longer in the case of a hanging or possible strangling, requiring a layered neck dissection. But the process starts with Rutherford reading the paperwork: medical history, work history, medications, how the body was found, what the person was last seen doing can all guide the way the autopsy is performed.

"We need a full picture. We don't just stick a knife into someone, bang, there goes the answer. It doesn't work like that." Moments of revelation are rare - Rutherford will often be mulling the cause of death weeks or months later. There are rules of thumb - if the external damage from a beating or accident isn't mirrored by obvious internal damage, it's hard to conclude the trauma caused death. Usually it comes down to judgment and experience.

"Theoretically any amount of trauma in a sensitive individual could cause death. We all have differences in the susceptibility of our heart muscle to abnormalities of rhythm. It's just the way we're programmed, just as some of us are programmed to have size 12 feet. You get a feel for the sorts of trauma that will definitely cause death, that might cause death or that are highly unlikely to cause death."

The difficulty in deaths such as Mulholland's is that the terror of an accident or beating can flood the body with adrenaline, making a weak heart stutter and eventually causing death. And like post-earthquake jitters, those effects can linger for minutes or even hours after the event. But the adrenaline can dissipate in seconds, leaving no trace to tell Rutherford of its significance.

"All I can tell is that the person has a scarred heart from previous heart attacks, so he will be more vulnerable to sudden abnormality of heart rhythm. I can see he's got a lot of bruising around the head, fractured nasal bones, so I know the beating has been substantial. And then I have to express an opinion."

In criminal cases that opinion can change lives, sending people to prison, or setting them free. It's a responsibility that "weighs hugely", Rutherford says. "I don't expect to go into a High Court, present my evidence and for it to be accepted. I expect to get a good rummaging by the defence. And if I don't, I'm disappointed and I feel that justice is not being done."

For all its unpleasantness, working daily with death brings answers to the grieving and "adds an element of value to life".

"The philosophers say you don't really know what life is until death looms. I think that's probably right."

The Southland Times