DNA contamination by examination instruments

Using DNA-analysis systems in forensic examination, conditions without any (iatrogenic) contamination are necessary for analysis of evidence. Failing these conditions a contamination is possible and interpretation of the results may be difficult. Our experiments demonstrated a relevant transfer of DNA-material if contaminated instruments were used.     

Using cement-containing powder glue (tile cement) to dispose of a cadaver

A 40 year-old woman was killed by fist and chop blows and buried in a forest area far away from the scene of the homicide. Before covering the body with soil the perpetrator poured 25 kg of tile cement powder over it. When the victim was retrieved 6 weeks later, the cement had hardened covering the body like a plate and encasing it like a sheath. The surface of the tile cement facing towards the body was found to contain two kinds of traces: detailed cast-like reproduction of the textile structures of the victim's clothing and wallpaper-like epidermal adhesions. By means of sequencing the mitochondrial DNA the adherent horny scales could be related to the victim.     

Physical and chemical evidence remaining after the explosion of large improvised bombs. Part 1: firings of ammonium nitrate/sugar and urea nitrate

Recent criminal acts in the United Kingdom, United States and other countries have demonstrated the dangers to public safety from the criminal use of improvised explosives on a large scale. Four sets of trials were carried out over four years, partly in collaboration with the United States Federal Bureau of Investigation, involving the firing of large bombs, mostly fertilizer based. The principal objectives of the firings were to measure the physical effects of the explosions upon objects representative of those that would be found at a real bomb scene and to recover any chemical traces deposited on these objects. The results are intended for use as an aid in determining the approximate size and type of an explosive employed in a terrorist attack. This paper describes the background behind the trials, the procedures for preparation of witness materials and charges, and the collection and analysis of physical and chemical evidence.     

A review of crane deaths in Jefferson County, Alabama

Cranes are machines used to move heavy objects. Cranes are operated by crane operators, usually working in conjunction with an assistant guiding the movements of the crane from his vantage point outside the crane. Few jurisdictions require that crane operators be either licensed or certified. We conducted a retrospective study of those dying of crane-related injuries in our jurisdiction during the 16 years from 1981 to 1996. All ten decedents were male, and the manner of each death was accidental. Neither ethanol nor drugs of abuse were detected in any case. Eight of the ten decedents died due to blunt force injuries, one due to mechanical asphyxia, and one due to thermal burns. Investigation by the Occupational Safety and Health Administration (OSHA) led to fines ranging from $80 to $2700 in six of the ten cases. Nationwide, electrocution is the most common cause of crane-related death, but no crane-related death in Jefferson County was caused by electrocution in our study. The absence of electrocutions was due to the planned, routine suspension of power to electrical lines in the vicinity of a crane during the crane's operation, a practice saving an estimated seven lives. Nevertheless, human error or lack of planning was still responsible for most of the deaths in our study. In addition to careful planning and adherence to safety standards established by planning, we recommend the mandatory licensure and certification of professional crane operators and the assessment of larger fines by OSHA for safety standard violations.     

Population genetics of nine STR loci in two populations from Brazil

The Short Tandem Repeats (STRs) D3S1358, HUMvWA31/A, HUMFIBRA/FGA, D8S 1179, D2S11, D18S51, D5S818, D13S317, and D7S820 were studied in two Brazilian populations (from Amazonia and S. Paulo) using the "AmpF1 STR Profiler Plus PCR Amplification Kit." The nine loci showed a combined discrimination power greater than 0.9999999999 and a chance of exclusion of 0.9999.     

Population genetics of the D1S1656, D12S391, and D18S535 loci in Asturias (North Spain)

Allele and genotype frequencies for three recently described short tandem repeat loci D1S1656, D12S391, and D18S535 were determined in a population sample from Asturias (North Spain). The loci were amplified using a fluorescence based PCR method and were typed automatically. No deviation from Hardy-Weinberg expectations were observed. The three loci proved to be highly discriminating and the allele frequencies observed are similar to those of the other European populations that have been typed for these loci to date.     

Obtaining fingerprints from mummified fingers: a method for tissue rehydration adapted from the archeological literature

Our laboratory was asked to help with the rehydration of mummified human fingertips that had been removed from a recently deceased, unidentified female. Using a solution that was found in the archeological literature, we were able to successfully rehydrate dermal tissues to the extent that fingerprints could be taken. We believe that this solution, which until now has not been described in the forensic literature, is effective, affordable, and relatively easy to produce and use.     

DNA typing of samples for polymarker, DQA1, and nine STR loci from a human body exhumed after 27 years

A body was exhumed from the ground after 27 years. Samples of femur bone, tooth, and a fingernail were collected and successfully subjected to DNA extraction, quantitation, amplification, and subsequently typed for DQA1, polymarker, and nine STR loci. All three types of samples were typed for D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S17, D7S820, and amelogenin using ABI Prism 377 DNA sequencer.     

The Frye hearing in Florida: an attempt to exclude scientific evidence

State Supreme Courts require a minimum threshold of reliability and acceptance in the scientific community for all medical and similar evidence to be admitted at trial. In Florida and some other states, the courts adhere to what is known as the Frye standard, whereas in most states and in Federal Courts, it is the so-called Daubert standard. The jurisdiction of the present case is Hillsborough County (Tampa), Florida. Forensic pathologists seldom, if ever, are requested to participate in such hearings, unlike their toxicological and basic science colleagues who are more involved in research methodology and technical procedures. The burden is on the proponent of the evidence to prove the general acceptance of both the underlying scientific principle of the test and procedures used to apply that principle to the facts of the case at hand. The trial judge has the sole discretion to determine this question and general acceptance must be established by a preponderance of the evidence. The authors describe in detail a hearing in a case in which they were all involved. One author (WQS) had researched and documented the original scientific methodology in the literature. The situation involved a car and tractor trailer crash with the two occupants of the car dying of multiple trauma, whereas the truck driver was not injured. Autopsy of the auto driver revealed multiple injuries with exsanguination, and only vitreous humor and liver tissue, but not blood, were tested for ethyl alcohol. The estate of the driver of the automobile brought suit against the owner of the trucking company for wrongful death. The plaintiff requested a Frye hearing to question the reliability of testing other body specimens to translate to probable blood alcohol level. The testimony, submitted documents, and eventual decision by the judge are discussed.     

Unusual cases of suicide among health care workers

We describe three unusual cases of suicide committed by health care workers. The aim of this paper was to analyze and evaluate the evidence of general diagnostic elements of poisoning in these cases.