Laura Houghteling Case Study

Introduction

On October 19th 1992 witnesses believed they saw twenty three year old Laura Houghteling leave her Bethesda home, not knowing in fact that it was Hadden Clark, a part time gardner who worked for the Houghteling family. What would follow this sighting, and the subsequent missing persons report of Laura Houghteling would be a fascinating murder investigation which would lead to a precedent setting conviction and the capture of a serial killer.

This report will investigate the method of Mitochondrial DNA analysis through the DNA typing method of RFLP or Restriction Fragment Length Polymorphism. The report will explore the mechanisms of the technique itself along with the benefits and limitations of the technique.

This case is

Bloodstains were also recovered from Laura’s mattress and other pillowcase through the use of the chemicals Ameeto Black and Luminol. The amount of blood found indicated to investigators that she had been murdered.

In 1991, scientists at the Department of Forensic Medicine, Bern, Switzerland investigated if “Some of the commonly used presumptive test reagents for identification of blood and semen could potentially affect the recovery of intact high-molecular-weight de- oxyribonucleic acid (DNA) from evidentiary samples. Thus, the capability of performing restriction fragment length polymorphism (RFLP) analysis on evidentiary samples could be compromised.”

Through their investigation they determined that “Except for the phenolphthalein treatment, the quantity of extractable, high-molecular-weight DNA obtained was comparable with that of untreated stains.” This knowledge allowed investigators to confidently test the recovered blood stains from Laura’s mattress and pillowcase and determine that they shared an origin with the pillowcase discovered in the

Andreasson, M. Nilsson, B. Budowle, H. Lundberg and M. Allen explained “Biological evidence materials found at a crime scene are sometimes degraded or yield insufficient quantities of DNA to enable a successful autosomal STR analysis. These samples are often analysed by sequencing of mitochondrial DNA (mtDNA) due to its high copy number per cell.”

Though Mitochondrial DNA was adequate in this case due to the positive RFLP Typing Analysis found in the samples of Laura’s brother and mother it is generally used as a last resort when other DNA Typing tests are not available. This is because “Mitochondrial DNA does not approach STR analysis in its discrimination power.”

Societal Impacts and Legal