Linking Serial Murder C. Gabrielle Salfati Department of Psychology John Jay College of Criminal Justice New York USA

Offender Profiling Research Classifying homicide and rape crime scenes Linking offender characteristics to crime scene types Cross-national comparisons Linking serial homicide and rape

Serial Homicide – what do we know? Assumptions & general beliefs: All serial homicides are sexual Offenders have ‘signatures’ Offenders are consistent across a series Most of the literature to date is based on assumptions of motivations that underlie all of these behaviours (clinical/treatment perspective) No empirical studies looking at if this holds up Problems of relying on motivation (for investigative purposes)

Linking - What do we need to know? 1.Can we link crimes to each other? How do we identify a series? How do we know the difference between series? What criteria do we use?

Crime 1Crime 2Crime 3Crime 4 Crime 5Crime 6 1.Can we link crimes to each other?

Establishing the link Crime 1Crime 2Crime 3Crime 4 Crime 5Crime 6 1.Can we link crimes to each other?

Linking - What do we need to know? 1.Can we link crimes to each other? 2.Can we link a series to a specific ‘type’ of offender?

Crime 1Crime 2Crime 3Crime 4 Offender B Crime 5Crime 6 Offender A

Linking - What do we need to know? 1.Can we link crimes to each other? 2.Can we link a series to a specific ‘type’ of offender? However: No research evidence to establish 1.If offenders are consistent 2.If they are, how this is displayed 3.What behaviours are the most reliable to focus on

Context Victim interaction Development/Maturation Experimentation Learning Consistency Issues

Physical (phenotypical) vs Psychological (genotypical) behaviour E.g. gagging & binding Separate behaviours But same theme of ‘control’ (behavioural ‘tool kits’) The Behavioural vs. Theme Focus

Behaviour vs.Theme How consistent are offenders across a series, and in what way. Study 1 Linking by using behaviours Study 2 Linking by using themes

Linking by using “behaviours”* Data from Washington State Homicide Investigation and Tracking System (HITS) 450 homicide cases committed by 90 offenders (5 cases each) * Bateman and Salfati (under review)

The behaviours Objective behaviours obtained by police from the crime scenes. Chosen from the literature on homicide. Chosen in order to make the results from the study directly applicable to investigators 6 categories, each containing a number of variables: Forensic awareness Body disposal Mutilation Weapon Theft Sexual activity

Forensic awareness & Control Crime kit Destroyed evidence Restrained/body bound Gagged Blindfold Face covered

Body disposal Movedafter homicide Hidden Openly displayed Posed Dressed Undressed Re-dressed

Mutilation Burned Body parts scattered Disfigured Tortured Dismembered Bite marks

Weapon Firearm/shot gun/rifle Stabbing or cutting Bludgeon or club Ligature Manual (hands/feet) Weapon brought to crime scene

Theft Clothing (panties/shoes) Monetary value

Sexual activity Sexually assaulted Oral by offender Oral sex victim to offender Vaginal sex Anal sex Antemortem Sex Postmortem Sex Foreign objects inserted Semen found

Consistency Analysis Analysis aims to determine if the offender was performing the behaviour how consistent they were at performing the behaviour throughout their series Average consistency % for behaviours within each category Average consistency % for each of the six broad categories calculated 4/5 crime scenes = 80% consistency

Consistency in serial murder TheftForensicWeaponSexualDisposalMutilation Overall consistency 83.9%80.8%77.0%73.1%68.7%67.4% 4/53/5

Consistency in serial murder TheftForensicWeaponSexualDisposalMutilation Overall consistency 83.9%80.8%77.0%73.1%68.7%67.4% 4/53/5 The inconsistently used types of behaviours are Many of those that are currently being used for linking ie signatures, sexual behaviours (using stringent criteria)

Linking by using “themes”* Data from Washington State Homicide Investigation and Tracking System (HITS) 69 homicide cases committed by 23 offenders (3 cases each) * Salfati and Bateman (2005) Serial Homicide: An Investigation of Behavioural Consistency. Journal of Investigative Psychology and Offender Profiling

OffenderVictim Knife Blunt Strangle

Typologies of homicide SSA based Crime Scene typologies of single homicide* Expressive – victim as person Instrumental – victim as object Each theme contained a number of behaviours. Offenders engaged in any number or varied combinations of these at a crime scene. Current study found similar distinction between crime scenes in serial homicide Question – how do we use the model to identify type of crime scene? * Block et al. 1998, Salfati and Canter 1999, Salfati 2000, Salfati and Haratsis 2001, Santilla et al 2001)

Instrumental BehavioursExpressive Behaviours Sexual assaultVictim was male Victim found partially dressedVictim was 15 years of age or less Body moved from discovery siteWeapon brought to scene by the offender Victim found nudeBody hidden Body recovery site was in or about victim's residenceOffender destroyed/attempted to destroy evidence Victim was 35 years of age or olderVictim was bound Body was staged or posedStabbing or cutting weapon used Weapon used was ligatureVictim was between 15 and 25 years of age Weapon used was offender's hands or feetVictim was between 25 and 35 years of age Weapon used was a bludgeonWeapon used was firearm Body displayed openly or to ensure discoverySmall personal items/trophies taken from victim Victim was gaggedVictim was tortured Unusual act, ritual or thing performed

Typologies of homicide SSA based Crime Scene typologies of single homicide* Expressive – victim as person Instrumental – victim as object Each theme contained a number of behaviours. Offenders engaged in any number or varied combinations of these at a crime scene. Current study found similar distinction between crime scenes in serial homicide Question – how do we use the model to identify type of crime scene? * Block et al. 1998, Salfati and Canter 1999, Salfati 2000, Salfati and Haratsis 2001, Santilla et al 2001)

Do crime scenes follow a pattern? Classification Strategy Total % of Cases Classifiable % of cases that could be classified as Expressive % of cases that could be classified as Instrumental 1 (simple)100 (N=69) (1½x)64 (N=44) (2x)41 (N=28)7525

Do crime scenes follow a pattern? Classification Strategy Total % of Cases Classifiable % of cases that could be classified as Expressive % of cases that could be classified as Instrumental 1 (simple)100 (N=69) (1½x)64 (N=44) (2x)41 (N=28)7525

Do crime scenes follow a pattern? Classification Strategy Total % of Cases Classifiable % of cases that could be classified as Expressive % of cases that could be classified as Instrumental 1 (simple)100 (N=69) (1½x)63 (N=44) (2x)41 (N=28)7525

Can we use this for linking? Do offenders consistently perform the same type of offending behaviours across their series of homicides?

Linking by theme? Classification Strategy Number of cases where all 3 cases belonged to the same dominant theme 113/23 = 56% 2 (1½x)6/23 = 26% 3 (2x)3/23 = 13%

Implications of results Some evidence of consistency, but: Offenders are mostly not thematically consistent (at least not using the current model & levels of stringency of classification) This highlights considerable problems with linking using current understanding of consistency

The Future Expand understanding of A-A-A issue Understand influences on consistency Evaluate what type of offenders are related to different type of series ie consistent series vs non-consistent series (Is this a particular pattern rather than a non- classifiable case?) Sexual vs non-sexual. Ongoing studies…

Ongoing & Future Studies Consistency – which behaviours are stable/influenced by victim/situation/learning etc. (& how) Single and serial Sexual vs non-sexual – behavioural vs motivational Theft and sex Length of series (& change) Cooling down period Age of victim and offender Victim type (prostitutes, known etc) Measurements of consistency (length of series) Criminal background/ongoing crimes Spree murders Replication – international & different datasets Issue of quality of data – measurements and reliability Homicide Profiling Index (HPI)

For copies of papers: For details of research on profiling: