The number of African elephants killed illegally for their ivory is rising steeply.
A poaching surge in the past five years is raising fears of a re-run of the catastrophic slaughter of elephants in the 1970s and 1980s.
During that period, referred to by some as the "ivory holocaust", Africa's elephant population plunged from an estimated 1.3 million animals to 500,000.
One team of scientists argues that, today, about 38,000 elephants across sub-Saharan Africa are dying annually at the hands of poachers to feed the growing demand for ivory carvings and trinkets in eastern Asia.
If that poaching rate is correct and is sustained, the elephant would become extinct across most of sub-Saharan Africa in fifteen years.
The calculation on which this figure is based is questioned by a number of other experts on the illegal ivory trade. They believe the overall slaughter rate is considerably lower.
Nonetheless, 20 years after the international trade in ivory was made illegal, there is widespread concern over the escalating problem.
According to Tom Milliken of the wildlife trade monitoring organisation, TRAFFIC: "Since 2004 there's been a rapidly increasing trend in the illegal ivory trade. And this is very worrying because it follows on from a progressive decline in the ivory trade."
In the last five years, the price of ivory has sky-rocketed.
There are reports of Asian dealers paying well in excess of US$1,000 per kilo - such is the demand from the burgeoning population of consumers in China, for example, who can now afford ivory products.
A combination of the soaring value and the fact that wildlife crime is a low priority for most law enforcement agencies means that ivory poaching and trafficking has attracted the interest of international criminal syndicates.
According to Sam Wasser of the Centre for Conservation Biology at the University of Washington, Seattle: "This has created a situation where organised crime has gotten very heavily involved in the illegal trade. In fact, if you look at all wildlife crime - not just ivory - there are tens of billions of dollars being made annually."
The slaughter of elephants is at its most rampant in the forests and bush of Central Africa, in countries such as the Democratic Republic of Congo where civil war, corruption and poor standards of governance make the animals particularly vulnerable. However, poaching rates are also rising in southern and East African countries.
Patrick Omondi, who is head of species conservation at the Kenya Wildlife Service, said that the number of elephants killed for their tusks in his country more than doubled between 2007 and 2008. The latest figures for 2009 suggest it may double again by the close of this year.
2009 has also seen a string of spectacular seizures of contraband ivory made by authorities in eastern Asia. In March, Vietnamese customs discovered a shipping container with 6.3 tonnes of tusks in Hanoi.
Within six weeks, another 3.5 tonnes was seized in Manila in the Philippines and another illegal shipment of one tonne was picked up in Bangkok, Thailand. The combined weight of just these consignments represents about 2,000 dead elephants.
Speaking on the BBC Radio 4 programme Last Chance for Africa's Elephants?, Peter Younger of the wildlife crime unit at the global police agency, Interpol, said: "These three seizures over that short a period of time are the largest seizures I've seen since I've been in this business."
They had been shipped out of Africa from Dar-es-Salaam in Tanzania, though the East African country is not necessarily the country where the elephants were poached.
Once ivory has been trafficked out of the continent, it is often impossible to identify where the tusks were originally poached.
According to Sam Wasser, the lack of this information has kept the criminals several steps ahead of law enforcement and allowed intense elephant killing to go unchallenged in areas where anti-poaching measures are not adequately enforced.
In a bid to fight back against the illegal trade, Professor Wasser has led the development of a DNA forensic technique which pinpoints the origin of seized ivory.
Over the last decade, hundreds of elephant dung samples have been collected and sent to his lab from all over sub-Saharan Africa.
DNA from each has been analysed. The team have focussed on 16 specific genes from the elephant genome and plotted how the specific genetic code of each one varies from location to location. This gives them a map of elephant genetic variation across the sub-continent.
Being an overgrown tooth, an elephant tusk also harbours the animal's DNA. So when Sam Wasser's team receives a piece of seized ivory - either raw or carved - they pulverise it to a powder and then chemically extract the DNA within. The make-up of the 16 genes is then compared to the dung DNA database.
Because populations of elephants living near each other are more genetically similar than populations further apart, a statistical analysis allows the Seattle lab to say where the poached ivory originated - sometimes to within several tens of kilometres.
According to Professor Wasser, this method is much less cumbersome than other ivory genetic marker techniques.
He also said that his DNA tests on impounded ivory shipments have revealed new information on the way the criminal syndicates of poachers and illegal dealers are operating.
The findings are contrary to a widely-held belief of law enforcement agencies, he told the BBC.
"They thought that the dealers who were shipping them were cherry-picking across Africa: taking bits of ivory from here and there, putting together a big consignment together and sending it out. We find that's not happening at all," said Sam Wasser.
"In fact they (the dealers) get a purchase order - we need so many tusks at such a time - and they go and hammer these populations over and over again - the same population. So they are doing major, major devastation."
For example, analysis of samples from two large illegal shipments in 2006 suggested that the Selous Game Reserve in southern Tanzania had become a hotspot of intense poaching. These seizures were 5.2 tonnes of ivory in Taiwan and 2.6 tonnes caught in Hong Kong.
Another Hong Kong seizure in 2006 contained 3.5 tonnes of tusks, hidden behind a false wall in a shipping container. It had left Africa from the port city of Douala in Cameroon.
Follow-up investigations revealed a second and third container with similar secret compartments. Both had chips of ivory on their floors. All three were owned by a Taiwanese national living in Cameroon.
Customs documents suggested at least 11 shipments to ports in East Asia. Although all the illegal exports came out of Cameroon, the Seattle DNA tests showed that most of the ivory originated from the south-east of neighbouring Gabon. According to Sam Wasser: "There wasn't a lot of indication of heavy poaching in Gabon so this exposed Gabon as a very significant poaching area."
Forensic techniques such as the geographic DNA test can help to reveal regions where anti-poaching measures need to be beefed up. They can also aid the investigations of how the big time ivory traffickers are operating.
However, many of the interviewees who spoke to BBC Radio 4 are daunted by the scale and international nature of the criminality involved. At Interpol, Peter Younger argues that much more concerted co-operation among African and Asian countries is necessary.
"In this particular area of crime, we're losing because the people we are tasked to deal with are much more co-ordinated than we are. We have a mechanism to co-operate. Interpol is the only international police agency, but there are other platforms. We are just not using them enough."
"Last Chance for Africa's Elephants?" is available on the BBC iPlayer. It was originally broadcast on BBC Radio 4. Andrew Luck-Baker will also be presenting two editions of "Discovery" on BBC World Service on the crisis facing the African Elephant on Wednesday 19th and 26th August