'Exactly. So the volatile fatty acid profile can provide an estimate of TSD.' TSD is the investigator's shorthand for 'time since death.'

'Did you get the National Weather Service data?'

He went to a set of shelves and returned with a printout.

'It was amazingly fast. Normaly it takes much longer. But we do have a slight problem. For a realy accurate TSD estimate I need three things. First, the specific fatty acid ratios.'

He pointed at a computer screen linked to the gas chromatograph.

'We'l have those shortly. Second, the National Weather Service data at the location where the corpse was found.'

He held up the printout.

'Third, information on the weight and condition of the corpse. And you ain't got no body.' He sang the last.

'Everyone's a comedian.'

'Two variables are important: the amount of moisture in the soil, and the weight of the body prior to decomposition. Because everyone has a different ratio of fat and muscle tissue, if I don't have a body, I use a standard of one hundred fifty pounds, then apply a correction factor. I think we're safe in assuming your deceased weighed between one hundred and three hundred pounds?'

'Yes. But in doing this, our range broadens, right?'

'Unfortunately. Did you try a rule-of-thumb estimate?'

Since volatile fatty acid liberation ceases at accumulated degree days 1,285 plus or minus 110, it is possible to obtain a rough estimate of time since death by dividing the average daily temperature on the day a corpse is found into 1,285. I'd done this for Lucy Crowe. Yesterday's average temperature in Bryson City was 18°C (64°F), yielding a maximum time since death of seventy-one days.

'That would be the date on which ful skeletonization had taken place, and no more VFAs would be detectable.'

Laslo looked at the wal clock.

'Let's see how accurate you were.'

He rose, filtered and vortexed the soil solution sample, tested its acidity, then placed the tube into the gas chromatograph. After closing and sealing the chamber, and adjusting the settings, he turned back to me.

'Let's give this a few minutes. Coffee?'

===OO=OOO=OO===

When we returned the screen showed a series of peaks in varying colors, and a list of components and their concentrations.

'Each curve shows the concentration of a volatile fatty acid per gram of dry weight of soil. First I'l correct for dilution and soil moisture.'

He hit a few keys.

'Now I can calculate an ADD for each VFA.'

He started with butyric acid.

'Seven hundred accumulated degree days.'

He performed more calculations, using each acid. With one exception the ADDs fel within the 675 to 775 range.