Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition1 Chapter 30 Serial Offenders: Linking Cases by Modus Operandi and Signature

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition2 Introduction to Crime Scene Assessment Outcomes possible from crime scene assessment include: Determining the physical, behavioral, and demographic characteristics of the unknown offender Developing post-offense behavior of the offender and strategies for apprehensions

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition3 Introduction to Crime Scene Assessment Developing interviewing strategies once the offender is apprehended Determining the signature of the offender Determining where the evidence may be located

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition4 Introduction to Crime Scene Assessment Information used for analysis may come from: Police officer reports Statements Crime laboratory results Photographs Videotapes of crime scenes Autopsy reports

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition5 Historical Perspective MO- modus operandi or method of operation Modus Operandi first appeared in literature in 1654 Chief Constable Major L.W. Atcherly of England used ten categories related to an offender’s modus operandi in 1879

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition6 Atcherly’s 10 Categories Classword Entry Means Object Time Style Tale Pals Transport Trademark

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition7 Trademark Atcherly’s trademark was the precursor of what would have been known as the signature today Trademark, according to Atcherly, was whether the criminal committed any unusual act in connection with the crime- such as changing clothes, poisoning the dog, leaving a note

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition8 What is a Killer’s Signature Also referred to as a killer’s psychological calling card Homicide detectives are trained to look for unusual characteristics: victim left in a certain position, beaten or raped with a certain instrument Subsequent killings of same type alert detectives to possible serial qualities

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition9 Differentiating MO and Signature MO is simply the way a particular criminal operates: Using a glass cutter to break into building Using a drill to open door locks Way entry was gained

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition10 Differentiating Modus operandi (MO) and Signature MO accounts for type of crime and property attacked, including the person, time and place of crime, tool or implements used, way of entry, how victim was caught, or how suspect represented himself to victim

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition11 Signature Versus Modus Operandi FBI Behavioral Science Units and representatives, such as John Douglas, advise MO of killer is only those actions necessary to commit the murder

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition12 Signature Versus Modus Operandi Signature is the killer’s compulsion to express themselves Imprint left at scene he feels psychologically compelled to satisfy himself sexually

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition13 Signature Versus Modus Operandi FBI defends the signature aspect of a killer, saying that the elements of personal expression will only develop more fully over time According to Douglas, person’s violent fantasies progress in nature over time, and develops a need to develop those fantasies

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition14 Signature Versus Modus Operandi According to Gerberth (1996), it is simply not enough to consummate the murder, the killer must act out fantasies in some manner. The acting out is the signature of the killer

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition15 Signature Versus Modus Operandi Detectives who investigate a series of murder scenes look for the same type of extraordinary violence and a set of bizarre similarities A signatures constitutes a strong possibility the same person is committing the crime

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition16 Items a detective or investigator may look for at a crime scene: How victim was placed, arrangement of crime scene, preoccupation with a certain aspect of the scene, mutilation, overkill, body carving, engaging in postmortem activity, making victim respond in a certain manner Signature Versus Modus Operandi

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition17 Signature Analysis Examples of clues to a serial killing in the Shoreline Murders Acts of binding occurring at consecutive murders Number of stabbing strokes necessary for killing Disposition of victim’s body- placement Taking of souvenirs Burning of bodies in certain areas

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition18 Statistical Analysis Homicide Investigation and tracking System (HITS) in Washington State is a central repository for murder and sexual assault victims in state of Washington System has 227 query capabilities Other states and federal agencies have similar systems

Chapter 30 CRC Press: Forensic Science, James and Nordby, 2nd Edition19 Catching the Killer Necessary items to catch a killer: Thorough investigation of crime scene Cooperation with all agencies involved Review all evidence from witnesses DNA analysis and laboratory analysis of evidence Coordinated efforts with prosecution