Using thermal information to detect unmarked graves will involve expertise
in interpreting the remotely sensed data and understanding the data
collection parameters.
Do you have the name of a sensor used for this? A platform ? A resolution?
The more information you have regarding where you heard about the technique,
the easier it will be for people to assist you.
As someone who works with data of this sort regularly, I can tell you that
spatial and spectral resolution will have significant impacts on one's
ability to detect these relatively small spatial features.  As well, the
climatic conditions, time of day, depth of graves and vegetative canopy will
also be factors affecting the most appropriate data acquisition time.
If you could provide more information about this, I would love to help if I
can.
In the meantime, a good reference is "Remote Sensing and Image
Interpretation 3rd ed." (1994) by Lillesand & Keifer (published by John
Wiley & Sons Inc.).  pp. 229 - 235 deal specifically with archaeological
applications and pp. 369 - 393 deal with thermal radiation principles and
interpreting thermal imagery.
Cheers,
Heather
        ----------
        From:  sbien [SMTP:[log in to unmask]]
        Sent:  Tuesday, March 20, 2001 10:27 PM
        To:  [log in to unmask]
        Subject:  Re. techniques for locating unmarked graves

        3-20-01

            I am looking for information on thermal sensing to locate
unmarked graves.  I am not exactly sure what the technique is called.  It
involves different temperatures of the soil showing up in different colors.

        S. Bien
        [log in to unmask] <mailto:[log in to unmask]>