The Body in the Bag

Presented By:•Jennifer Fitzmaurice•Martha Fimowicz•Karen Kuklewicz

Case Background

• Late Spring in the morning, an elderly

retiree with a fishing pole, walks through

the underbrush that lined the river’s bank.

• He nears the shore and

sees a rather large canvas

bag floating in the water,

held by the foliage that

leaned over the river.

Case Background

• The bag appears to be stuffed, well worn

and heavily stained.

• Upon further inspection he sees what he

believes to be hair floating through the

bag’s opening.

• He marks the spot and notifies the

authorities.

Case Background

• Preliminary investigation at the scene

revealed a body in the bag.

• The body’s sex, age and race can not be

immediately identified.

• Forensics is assigned

the task of identifying the

victim and estimating the

cause and time of death

Tasks of the Detectives

• Develop a preliminary profile of the victim and offender.

• Only information that the detective has is that the victim and offender are both adults (over 18 years of age).

• Information gathered by the detective in charge concerning victim/offender relationships from the Uniform Crime Reports from the FBI (2003).

Race of Victim/Offender

Race of Offender

Race of Victim

White Black Other TOTAL

White 3017 501 44 3562

Black 226 2864 8 3098

Other 47 26 122 195

Unknown 33 21 2 56

TOTAL 3323 3412 176 6911

Sex of Victim/Offender

Sex of Offender

Sex of Victim

Male Female Unknown TOTAL

Male 4417 499 71 4987

Female 1754 185 23 1962

Unknown 49 7 19 75

TOTAL 6220 691 113 7024

Victim Profile

Based on the information from Uniform Crime Reports from the FBI (2003);

What is the best prediction of the

race and sex of the offender?

Race of Victim

Race of Victim

TOTAL

White 3562

Black 3098

Other 195

Unknown 56

TOTAL 6911

Race of Victim

TOTAL

White 51.5%

Black 44.8%

Other 2.8%

Unknown 0.8%

TOTAL 100%

Sex of Victim

Sex of Victim

TOTAL

Male 4987

Female 1962

Unknown 75

TOTAL 6911

Sex of Victim

TOTAL

Male 71.0%

Female 27.9%

Unknown 1.1%

TOTAL 100%

Victim Profile

• White Male• Probability is Classical Probability• Probability Rule is that the Probability

Value must be between 0 and 1• Where the Probability of the Victim

being White is 3562/6911 = 51.5%• Where the Probability of the Victim being Male is 4987/7024 = 71.0%

What is the best prediction as to the race and sex of the

offender?

Offender Details: Race

Race Total

White 3,323

Black 3,412

Other 176

Total 6,911

Race Total

White 48.1%

Black 49.4%

Other 2.5%

Total 100.0%

Offender Details: Sex

Race Total

Male 6,620

Female 691

Unknown 113

Total 7,024

Race Total

Male 88.6%

Female 9.8%

Unknown 1.6%

Total 100.0%

Offender Profile

• Black Male• Probability is Classical Probability• Probability Rule is that the Probability

Value must be between 0 and 1• Where the Probability being Black is

3,412 / 6,911 = 49.4%• Where the Probability being Male is

6,620 / 7,024 = 88.6%

How likely is that the victim and the offender are of the same race? Same gender? And does it agree with the preliminary predictions?

Joint Profile: Race

Offender Total

White 48.1%

Black 49.4%

Other 2.5%

Total 100.0%

Victim Total

White 51.5%

Black 44.8%

Other 3.6%

Total 100.0%

Joint Profile: Race

P(white) 48.1% * 51.5% = 24.8%

P(black) 49.4% * 44.8% = 22.1%

Probability is Classical Probability with multiplication rules. The method for finding the probability that both of two events occur.

Joint Profile: Sex

Offender Total

Male 88.6%

Female 9.8%

Unknown 1.6%

Total 100.0%

Victim Total

Male 71.0%

Female 27.9%

Unknown 1.1%

TOTAL 100%

Joint Profile: Sex

P(male) 88.6% * 71.0% = 62.9%

P(female) 9.8% * 27.9% = 2.7%

Probability is Classical Probability with multiplication rules. The method for finding the probability that both of two events occur.

Joint Profiles

• The joint profiles for race of the individuals state it is 22.1% likely they are black and 24.8% they are white.

• For the sex of the victim and offender, it is 62.9% likely that they are male and 2.7% they are female.

• The joint profile analysis agrees for gender but does not for race.

Preliminary Forensic Report

• Autopsy suggested that the body had been in the water at least two weeks

• Victim was a white female with blonde hair

• She was estimated as being in her mid-thirties, showed no signs of having had children, and was wearing no jewelry.

Race of Offender

Race of Offender

Race of Victim

White Black Other TOTAL

White 3017 501 44 3562

Black 226 2864 8 3098

Other 47 26 122 195

Unknown 33 21 2 56

TOTAL 3323 3412 176 6911

Sex of Offender

Sex of Offender

Sex of Victim

Male Female Unknown TOTAL

Male 4417 499 71 4987

Female 1754 185 23 1962

Unknown 49 7 19 75

TOTAL 6220 691 113 7024

Offender Profile

• Race of offender in percentage

• Sex of offender in percentage

Race of Offender

TOTAL

White 84.7%

Black 14.1%

Other 1.2%

Sex of Offender

TOTAL

Female 9.4%

Male 89.4%

Unknown 1.2%

Offender Profile

• White Male

• Probability is Classical Probability

• Where the Probability of the Offender being White is 3017/3562 = 84.7%

• Where the Probability of the Offender

being Male is 1754/1962 = 89.4%

QUESTIONS?