Investigation of the Violent Crime Exemplar

Cause of Death and Odds of Occurrence

DiseaseHeart AttackCancerAuto AccidentSuicideHomicide

1 in 1.31 in 31 in 51 in 421 in 811 in 84

Homicide Investigation

• There are about 25,000 homicides a year.

• Some years up to 65% of homicides are solved by the arrest of the perpetrator.

LAW of Homicide

• 1st Degree: (cold-blooded murder) proof of premeditation, deliberation, & malice. (planning, coolness, scheming)

• 2nd Degree: (hot-blooded murder) proof of malice aforethought & intent to do bodily harm.

• Voluntary Manslaughter: (heat of passion) proof of provocation & no time to cool off. (self-defense is common defense)

• Involuntary Manslaughter: (accidents) reckless disregard of the consequences. (insanity)

ADAPT

• Assess Scene

• Detain Witnesses

• Arrest Perpetrator

• Protect the Scene

• Take Notes

Estimating Time of Death

• Body Temperature:– Bodies cool down after death.– The temp drops from 98.6 by a factor of

3 degrees in the first hour and a factor of 1 degree each subsequent hour.

– After 30 hours, decomposition causes the temp to rise.

– See chart in Lecture 1 Packet.

Estimating Time of Death

• Rigor Mortis– The body is limp until 6 hours after

death.– Hardness begins around jaw area and

spreads through body.– By 36 hours after death the body is

limp again.

Estimating Time of Death

• Lividity– The effect of gravity on the body– After death all of the loose blood in the

body runs down to the lowest point of gravity.

– Causes bluish-purple stains.– Begins after 3 hours and blood is dried

by 12 hours.

Estimating Time of Death

• Eyes– Eyes dilate 7 hours after death.

– After 12 hours, the eye becomes cloudy.

Estimating Time of Death

• Food– Anything undigested was eaten in

last 2 hours.

– Food spends 6 hours in small intestines and 12 hours in large intestines.

Estimating Time of Death

• Underwater Victims– Average dead person sinks for 8-10

days. (depending on weight)

– On or about day 11, bodies will begin to float.

Estimating Time of Death

• Decomposition & Entomology– Decomposition begins after 30 hours– Over time it causes a bloated greenish tint.– Blowflies – Green Bottle Flies lay eggs on

dead bodies which become maggots.– Measure largest maggot in mm + 2 =

approximate # of days since death.

Greem Bottle Fly – AKA: Bowfly

Sexual Assaults

• Any victim of sexual assault should be examined by:– SART: sexual assault response team.

– SANE: sexual assault nurse examiner.

Sexual Assaults

• Evidence may include: DNA, fingerprints, hairs, fibers, & blood.

• “The logical solution to a rape case involves matching trace evidence from three places: the crime scene, the victim and the perpetrator.”

Sexual Assaults

• Most forcible rapists claim to be a victim of mistaken identity… they claim they are not the perpetrator.

• Once evidence identifies them, they claim it was consensual sex.

Sexual Assaults• Some rapists use drugs to erase the

memory of their victims.– Gamma-hydroxybutyric (GHB)– Rohypnol– Ecstasy• Victim is often unaware of crime until it

is too late for most examinations to be helpful.

Sexual Assaults

• Last type of sexual offender targets children

• Offenders may be someone the victim knows.

• Many children are reached via the internet.

Motive, Means & Opportunity

• Motive: Purpose, reason, grounds.

• Means: Who has the physical strength to commit this particular crime.

• Opportunity: who had access to or could have been present at the crime scene.