MatchY in practice: Factors influencing pedigree-based Y-STR match probabilities

Area of Science:

• Forensic genetics
• Population genetics
• Computational biology

Background:

• Traditional Y-STR match probability calculations using population databases have limitations.
• These databases may not accurately represent case-specific suspect populations.
• A pedigree-based mathematical framework was previously developed to address this limitation.

Purpose of the Study:

• To explore factors influencing Y-STR match probabilities calculated with the MatchY software.
• To introduce a new 'trace mode' in MatchY for forensic intelligence.
• To provide guidance on using MatchY in routine forensic casework.

Main Methods:

• Utilized a previously established mathematical framework for Y-STR match probability calculation.
• Extended and implemented the framework in the publicly available MatchY software.
• Explored marker and pedigree-based factors impacting match probability outcomes.
• Introduced and evaluated a 'trace mode' for forensic intelligence.

Main Results:

• The MatchY software allows calculation of Y-STR match probabilities for various Y-STRs and pedigrees.
• Identified key marker and pedigree factors influencing match probability outcomes.
• Demonstrated the utility of MatchY's 'trace mode' for forensic intelligence applications.
• Provided practical guidance for using MatchY in casework with or without suspects.

Conclusions:

• The MatchY software provides a robust tool for calculating Y-STR match probabilities based on male pedigrees.
• Understanding marker and pedigree influences is crucial for accurate probability estimation.
• MatchY enhances forensic intelligence and offers valuable applications for routine casework.