Sexual Assault Evidence Kit (SAEK) Processing
The sheer volume of sexual assault evidentiary samples submitted to forensic laboratories has compelled many laboratories to seek better solutions for processing these challenging samples. Promega offers several products that take you through each step in the sexual assault evidence kit (SAEK) workflow, from sample extraction to analysis.
The Casework Direct System, when used with the PowerQuant® System, offers an ideal workflow to screen SAEK samples. The Casework Direct System rapidly generates lysates from casework samples that may be amplified with the PowerQuant® System to screen SAEKs for male DNA and to normalize human DNA templates for STR amplification with one of the PowerPlex® Systems.
SAEK Processing Workflow
Choosing a Workflow
Do you go the serology route or the Direct to DNA route? While serology may be familiar to many forensic laboratories, a “direct to DNA” approach using Y screening can save time and money.
|Serology||Direct to DNA/Y Screening|
|Low throughput and labor-intensive||High throughput; can be automated for even more efficient processing|
|All samples must be processed, regardless of whether they contain male DNA||Y screening eliminates samples that do not contain male DNA|
|Limited sensitivity to detect male DNA||High sensitivity, even with challenging samples, and improved effectiveness than what is seen with biological fluid screening for detecting male DNA from vaginal swabs, external genitalia, and dried secretions|
|Higher cost per sample||Eliminating unsuitable samples and direct STR amplification of qualifying samples lower SAEK processing costs|
|Poor results seen when samples are aged or improperly stored due to breakdown of enzymes used in serological screening||A better predictor of the success of obtaining a DNA profile where enzymes that detect biological fluids may have degraded|
Solutions for a Complete Workflow
Promega offers instruments, reagents and kits to support every step of the SAEK processing workflow.
|Preprocessing and Differential Extraction||DNA Isolation||DNA Quantification||Amplification/STR Analysis|
|Casework Direct System
Rapidly process SAEK and touch DNA samples
|Maxwell® FSC DNA IQ™ Casework Kit
Automated benchtop DNA extraction from casework samples
Quantify autosomal and Y-chromosomal DNA and assess sample integrity
|PowerPlex® Fusion System
Amplify and detect 24 loci, including CODIS core and ESS
Separate sperm and epithelial cells
|Maxprep™ Liquid Handler
Complete robotic system for nucleic acid purification
|Plexor® HY System
Simultaneously quantify autosomal and Y-chromosome DNA
|PowerPlex® Y23 System
Amplify and detect 23 Y-STR loci
Why Use a Y-STR System for Your SAEK Workflow?
Y-STR analysis can provide clues in situations where autosomal STR analysis has not yielded sufficient information to help the investigation. For example, excess amounts of female DNA can often make it difficult to detect male DNA when performing autosomal STR analysis. Because Y-STR kits, such as the PowerPlex® Y23 System, are designed to amplify male DNA, they are ideal for determining the number of male contributors in a mixture, detecting male DNA from cases where the perpetrator did not ejaculate or had undergone a vasectomy, or where penile penetration did not occur.
Learn more about the PowerPlex® Y23 System.
SAEK Workflow Resources
Webinar: Implementing a Y-Screening/Direct to DNA Forensic Workflow
The Palm Beach County Sheriff's Office describes their journey through SAEK workflow development, validation and implementation.
White Paper: Stability Testing of Casework Direct Lysate
Results from studies examining long-term storage and freeze-thaw cycling of Casework Direct lysates.
White Paper: Developmental Validation of the Casework Direct Kit, Custom
Validation studies based on requirements listed in the FBI QAS and SWGDAM guidelines.