DNA analysis

NOTE: To assist you in understanding this document, the Crime Lab prepared a tutorial on Multiplex STR DNA analysis.

 

YOKNAPATAWPHA COUNTY FORENSIC LABORATORY

REPORT DATE: July 15, two years ago

Madeline Holland, Ph.D.
555 Jackson Avenue
Oxford, MS 38655
662-234-XXXX (FAX 662-234-XXXX)

Analysis: Multiplex STR

Case: 003502

Case Description: Philip Fontaine Homicide

Investigative Agency: Yoknapatawpha County Sheriff's Department

Investigating Officer(s): Det. S. Murphy. Det. T. Armstrong

 

Evidence Item Description

003502-04-02A

Chef's knife ‒ Sample location: 5cm from tip
Electropherogram 003502-04-02A

003502-04-02B

Chef's knife ‒ Sample location: tip of blade
Electropherogram 003502-04-02B

003502-04-02C

Chef's knife ‒ Sample location: handle
Electropherogram 003502-04-02C

003502-04-02D

Chef's knife ‒ Sample location: blade/handle junction
Electropherogram 003502-04-02D

003502-S01

Blood sample from Philip Fontaine
Electropherogram 003502-S01

003502-S02

Presumed blood smear located on Philip Fontaine's left cheek
Electropherogram 003502-S02

003502-S03

Pooled blood near body on kitchen floor
Electropherogram 003502-S03

003502-S04

Presumed bloody fingerprint on kitchen cabinet door
Electropherogram 003502-S04

003502-S05

Shoeprint on kitchen floor
Electropherogram 003502-S05

003502-S06

Red substance on broken glass
Electropherogram 003502-S06

003502-S07

Red droplet on kitchen floor
Electropherogram 003502-S07

003502-S08

Red droplet on kitchen floor
Electropherogram 003502-S08

003502-S09

Red substance on kitchen sink
Electropherogram 003502-S09

Findings:

Items 003502-04-02A and 003502-04-02D are positive mixtures as noted by 3 to 4 peaks at several loci.  By comparing the electropherogram of the victim (003502-S01), items 003502-04-02A and 003502-04-02D contain the victim's DNA. 

Items 003502-04-02B, 003502-S03, and 003502-S05 can be conclusively matched to the victim (1 in 625,000,000 probability that the samples do not belong to the victim). 

Items 003502-04-02C, 003502-S02, 003502-S04, 003502-S06, 003502-S08, and 003502-S09 represent an unknown donor who has contributed to items 003502-04-02A and 003502-04-02D. (1 in 750,000,000 probability that the unknown donor does not contribute to said items).

Item 003502-S07 represents a third donor inconsistent with the victim or the previous unknown donor. 

All unknown donors are male (Amelogenin locus containing 2 peaks).