Forensic DNA Identification from Human Remains Submerged in Water

By Cheryl M. Lowe

April 29, 2009

Background

• There are many incidences where human remains end up in water

• What are the distinguishing features of human remains found in water?

• Is there a difference between salt water and fresh water in regard to DNA preservation?

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Background

• There are many factors that affect the integrity of DNA evidence from remains found in water

• Limited research so far on how long DNA can be preserved in water

Definitions

• Seawater = water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5%, or 35 parts per thousand

– The density of surface seawater ranges from about 1020 to 1029 kg·m-3, depending on the temperature and salinity

• Fresh water = naturally occurring water on the surface such as bogs, ponds, lakes, rivers and streams and underground in aquifers and underground rivers

– Low concentrations of dissolved salts– coastal areas freshwater may contain

significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the clouds

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Total Molal Composition of Seawater (Salinity = 35)

Component Concentration (mol/kg)

H2O 53.6

Cl- 0.546

Na+ 0.469

Mg2+ 0.0528

SO42- 0.0282

Ca2+ 0.0103

K+ 0.0102

CT 0.00206

Br- 0.000844

BT 0.000416

Sr2+ 0.000091

F- 0.000068Source: http://en.wikipedia.org/wiki/Seawater

Remains Submerged in Water

• Favorable conditions for adipocere

• Increased saponification due to exposure to excess of water

• Cells absorb water until rupture, then release fatty contents that are then hydrolyzed and hydrogenated

• Adipocere is common in remains found in bathtubs, ponds, lakes, oceans

• Bloating, skin slippage, wrinkling of hands and feet common

O’Brien, et al.

Remains Submerged in Water

• Tissue loss from:– Effects of the water

current– Chemical composition

of water– Industrial waste water– Predation by insects,

marine animals, fish

O’Brien, et al.

Body at 4 weeks

O’Brien, et al.

Body at 7 weeks

O’Brien, et al.

Body at 12 weeks

O’Brien, et al.

Stages of adipocere formation on a body floating in water for

3 months

Stage I – 4 Float, bloat, ovapositioning and hatching

Stage II 4–6 Early: insect activity, skin sloughing, cutis anserina, residue formation on water surface

Stage III 6–8 Early: adipocere formation, microbial growth, color loss; Increased: insect activity, skin sloughing, cutis anserina, residue formation on water surface

Stage IV 8–10 Increased: adipocere formation, microbial growth; Advanced: insect activity, cutis anserina, color loss, residue formation on water surface

Stage V 10–12 Advanced: adipocere formation, microbial growth; Reduced: insect activity

O’Brien, et al.

Case Example – Fresh Water

• Decomposed remains found in a dam on the Seine River after 3 years

• Successful recovery of DNA profiles using Profiler Plus kit from bone (10 STR loci and amelogenin)

• No results from saponified sternocleidomastoid muscle

Case Example – Fresh Water

Case Example – Fresh Water

Case Example – Salt Water

• Skeletonized remains found in 2 rubber boots in March 2005, 145m deep in the Southern Australian coast (Great Australian Bight)

• DNA analyses on reference samples from relatives of fishermen who had disappeared in the area

• Victim identified with Profiler Plus kit as a 52 year old prawn fisherman, swept off of boat about 10 years earlier

Case Example – Salt Water

• DNA stability maintained by low light conditions, cold temperatures, alkaline pH of the ocean floor (pH was between 7.5 and 8.5)

Byard, et al.

Case Example – Salt Water

• Remains found relatively preserved within rubber boots

• Wedges of bone from distal ends of each tibia were submitted for DNA analysis

• Homicide with dismemberment was considered as a possible scenario

• Possibility of drifting of remains along the ocean floor…could have come from coastal areas

DNA Profiles Obtained

Byard, et al.

DNA Stability in Water

• DNA integrity can be preserved under the following conditions:– High mineral content of water: high amounts of

calcium, magnesium, carbonates, sulfides, sulfates

– Anaerobic environment: limits oxidative damage of DNA, as well as bacterial and fungal growth

– Neutral pH: around 6.1 to 6.9, buffered from presence of carbonates

– Low oxygen tension

DNA Stability in Water

• From 1984 to 1987, there were 177 ancient individuals of all ages recovered from Windover pond, Florida Atlantic Coastal Ridge

• Intact crania with pieces of preserved brain matter• Pond possessed favorable conditions for DNA

preservation; preliminary Southern blot showed traces of human DNA

Discussion

• Water can preserve DNA evidence in most cases

• The most important factor in the recovery of DNA evidence from submerged remains seems to be time

• However, it can sometimes complicate data…especially in mass disaster investigations (Southeast Asian tsunami)

Conclusions

• DNA identification by itself is not fully reliable from human remains found in aqueous environments

• Important for other metadata to be incorporated, such as dental identification, anthropological studies

• Further research needs to be done

Bibliography

1. Crainic K, Paraire F, Leterreux M, Durigon M, Mazancourt P. Skeletal remains presumed submerged in water for three years identified using PCR-STR analysis. J Forensic Sci, Sept. 2002, Vol. 47, No. 5. (1-3)

2. Byard RW, Both K, Simpson E. The identification of submerged skeletonized remains. American Journal of Forensic Medicine and Pathology. March 2008, Vol. 29, No. 1, pages 69-71.

3. O’Brien TG, Kuehner AC. Waxing grave about adipocere: soft tissue change in aquatic context. J Forensic Sci, March 2007, Vol. 52, No. 2, 294-301.

4. Herrmann Bernd, Susanne Hummel. Ancient DNA: Recovery and Analysis of Genetic Material from Paleontological, Archaeological, Museum, Medical, and Forensic Specimens. Springer, 1994. Pages 105-106.

5. Graw M, Weisser HJ, Lutz S. DNA typing of human remains found in damp environments. Forensic Science International 113 (2000) 91-95.

6. Pacher J, Cameron J. Submersion cases: a retrospective study 1988-1990, Med. Sci. Law 32 (1992) 15-17.

7. Swann H, Spafford N. Body salt and water changes during fresh and sea water drowning, Texas Rep. Biol. Med. 9 (1951) 350-384.

Questions?

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