Latent Print Development - National Criminal Justice Reference ...

C H A P T E R 7 Latent Print Development
et al., 2004, p 128; Almog, 2001, pp 177–209; Pounds et
al., 1990, pp 169–175; Didierjean et al., 1998, pp 163–167),
applying a 160 °C iron for 20–30 seconds (Stoilovic, 1993,
pp 141–153), or applying a 180 °C ironing press for 10
seconds (Almog, 2001, pp 177–209; Stoilovic, 1993, pp
141–153). The reaction must be carried out in a dry environment
with low humidity because moisture interferes with
the development reaction (Champod et al., 2004, p 129;
Almog, 2001, pp 177–209; Wilkinson, 2000a, pp 87–103).
After DFO application and heating, developed fingerprints
can be observed using 530 nm excitation light and a 590
nm barrier filter, or 555 nm excitation light and a 610 nm
barrier filter (Almog, 2001, pp 177–209). The exhibit may
then be treated with ninhydrin as previously described.
7.6 1,2-Indanedione
7.6.1 History
The fingerprint-developing capabilities of 1,2-indanedione
were first considered after a related compound, 6-methylthio-1,2-indanedione,
was found to produce fluorescent
fingerprints (Hauze et al., 1998, pp 744–747). This prompted
researchers to synthesize the parent compound and several
other analogues and to evaluate their utility as fingerprint
reagents (Ramotowski et al., 1997, pp 131–139). The results
were similar to DFO in that a faint, pink-colored product
was produced that fluoresced brightly at room temperature
(Ramotowski et al., 1997, pp 131–139). Further research
indicated that these reagents are more sensitive than
other current methods and, because of the ease of synthesis,
can be a cheaper alternative (Cava et al., 1958, pp
2257–2263; Dayan et al., 1998, pp 2752–2754; Joullié and
Petrovskaia, 1998, pp 41–44). In the eight years following
7–20
FIGURE 7–7
DFO-developed fingerprint.
Left, under ambient light.
Right, excited by a
forensic light source
and viewed through the
proper viewing filter.
these discoveries, 1,2-indanedione has become a standard
reagent in Israeli laboratories and has been investigated for
use in many other countries (Almog, 2001, pp 177–209).
7.6.2 Theory
1,2-Indanedione is a close analogue of ninhydrin and is
theorized to react with amino acids in a very similar fashion
(Petrovskaia et al., 2001, pp 7666–7675). The structure of
1,2-indanedione has been characterized (Wilkinson, 2000b,
pp 123–132) and is illustrated in Figure 7–8(A).
Mechanistic studies of 1,2-indanedione’s reaction with
amino acids have indicated that the presence of methanol
desensitizes the reagent (Wilkinson, 2000b, pp 123–132).
Like DFO, indanedione forms a hemiketal with methanol;
however, unlike DFO, this hemiketal is more stable than
the parent compound and thus its formation prevents
the reaction with amino acids. Because 1,2-indanedione
is completely converted to the less sensitive hemiketal
(Wilkinson, 2000b, pp 123–132), some suggest that
alcohols should be avoided in any indanedione formulations
(Wilkinson et al., 2005; Wiesner et al., 2001, pp
1082–1084). Other studies have not corroborated this lack
of sensitivity in methanolic solution (Roux et al., 2000, pp
761–769). Similar ambiguity exists on the addition of acetic
acid (Lennard et al., 2005, p 43); some authors have found
that a small amount of acetic acid improves the results
(Hauze et al., 1998, pp 744–747; Joullié and Petrovskaia,
1998, pp 41–44), whereas others have experienced blurry,
unclear fingerprints when using acidified solutions (Almog,
2001, pp 177–209; Wiesner et al., 2001, pp 1082–1084;
Kasper et al., 2002). These discrepancies have been linked
to the acid content of the paper produced in the authors’
various countries (Wilkinson et al., 2005).