Tag Archives: DNA

Two Interesting Cold Case Articles

The first article has Michigan ties. Following up on a cold case led an Ohio medical examiner’s office to a fingerprint match and old files in Grand Haven that ID’d a man killed by a train in 1980. Via The Grand Haven Tribune

The second is another story of using ancestral DNA, this time to identify an abandoned child, which led to clearing a cold case on the other side of the country. From Forensic Magazine

Family DNA Article from the New York Times

Family DNA Searches Seen as Crime-Solving Tool, and Intrusion on Rights

Personally, I fail to see the intrusion on rights, but it’s an interesting article about DNA technology. Family searches aren’t even new, it’s something that’s been done for more than a decade in some places.

Tools for Improving the Quality of Aged, Degraded, Damaged, or Otherwise Compromised DNA Evidence

By Michael M. Cox, Ph.D., Evelyn M. Mercer
Published by the NIJ

Abstract
Almost every day, DNA samples are collected from the scenes of crimes or disasters that are too degraded for standard forensic DNA analytical procedures. This fact represents an ongoing impediment to law enforcement and victim identification efforts. Many law enforcement agencies also possess archived crime scene evidence from cold cases that are decades old, in which the DNA has become too damaged to analyze. The major problem in these samples is the presence of DNA double strand breaks. The purpose of the work carried out under grant 2010-DN-BX-K190 is to develop a new method to repair double strand breaks in forensic DNA samples, as a pretreatment for the standard STR analysis protocols. As part of this effort, we have also developed reproducible procedures for the artificial degradation of human DNA samples, using ionizing radiation to inflict a DNA damage profile that reprises that of a typical degraded forensic sample. Using this type of DNA as a test bed, we have developed a protocol that is successful in increasing/restoring missing or substandard signals at two STR loci. The protocol utilizes the bacterial RecA protein, single-stranded DNA binding protein (SSB), and bacterial DNA polymerase I, in concert with a targeting oligonucleotide. The reactions promoted by these reagents effectively restore damaged DNA flanking a particular STR locus. With the most developed protocol, signal restoration is successful approximately 20% of the time. With a few exceptions, the restored signals are accurate. The artifacts arising in the exceptions have been traced to the targeting oligonucleotides. Efforts to further develop this technology are continuing, focused on new RecA protein variants that increase signal strength and re-designed targeting oligonucleotides.

We have also been successful in demonstrating proof of principle in efforts to recover targeted DNA segments and remove them from bulk DNA in an effort to concentrate them and eliminate conditions that could inhibit STR amplification.

Read the full paper Here

New Study on Survivability of DNA Evidence

A new study published by the NIJ, demonstrates positive recovery of DNA for up to 10 days following intercourse. Given various circumstances that may lead to delays in reporting or testing, it’s good to know that current testing methods may still yield results even with a substantial delay.

The study can be accessed here (in .pdf format):  https://www.ncjrs.gov/pdffiles1/nij/grants/248682.pdf

Condom Trace Evidence: A New Factor in Sexual Assault Investigations

By Robert D. Blackledge, M.S.
Mr. Blackledge is senior chemist at the Naval Criminal Investigative Service Regional Forensic Laboratory in San Diego, California.

This Article Originally Appeared in the FBI Law Enforcement Bulletin, May 1996.

(Offenders are changing the nature of sexual assault investigations by wearing condoms.)
In an age filled with potentially fatal sexually transmitted diseases, more and more individuals practice safe sex. Even perpetrators of sex crimes have begun to wear condoms.1 It is not likely that a fear of disease prompts this behavior. Rather, just as a burglar dons gloves to avoid leaving fingerprints, sexual offenders now wear condoms to avoid depositing seminal fluids. Continue reading

Burglary Investigations

By Daryl W. Clemens

Burglary defined

Burglary is sometimes also known as Home Invasion, or Breaking and Entering. The unlawful entry into the premises of another with intent to commit a felony (usually larceny) therein.

Introduction

Burglaries represent one of the more common crimes to which patrol officers respond. Someone has returned home from an evening out and found the doors open and their property missing. The police are called, and an investigation is begun. Continue reading