Efficient DNA Sampling in Burglary Investigations

Area of Science:

• Forensic Science
• Genetics
• Criminology

Background:

• Burglaries are Switzerland's most frequent mass crime, contributing significantly to DNA databases.
• Distinguishing perpetrator DNA from inhabitant DNA at burglary scenes is a challenge.
• Reference samples from all residents are often not collected due to practical constraints.

Purpose of the Study:

• To evaluate the proportion of non-perpetrator (inhabitant) DNA profiles in burglary investigations.
• To determine the efficacy of DNA trace collection methods in identifying burglars versus residents.

Main Methods:

• Collected reference DNA samples from residents of burglarized homes.
• Compared these reference profiles with DNA traces recovered from crime scenes.
• Analyzed the location of DNA trace recovery (e.g., window/door glasses) in relation to the source (perpetrator vs. inhabitant).

Main Results:

• The majority of DNA samples collected at burglary scenes originated from the home's inhabitants.
• Despite a small sample size, the study indicated that DNA traces near entry points (window/door glasses) are more likely to be from perpetrators.

Conclusions:

• Current DNA trace collection in burglaries frequently yields inhabitant DNA, potentially leading to database misattributions.
• Targeted DNA collection at points of entry may enhance the identification of burglary perpetrators.