Tom Pakkanen

Åbo Akademi University · Department of Psychology

The increasing portrayal of forensic investigative techniques in the popular media—CSI, for example, has resulted in criminals becoming "forensically aware" and more careful about leaving behind physical evidence at a crime scene. This presents law enforcement with a significant problem: how can they detect serial offenders if they cannot rely on p...

This study examines the recidivism rates of Finnish child sex offenders convicted in 2010 (n = 361) over a follow-up period of seven years. The results indicate that while reoffending for other types of offences was common (34%), offenders had very low sexual crime recidivism rates (1%). In terms of more persistent criminal careers, less than a qua...

Purpose – Crime linkage analysis (CLA) can be applied in the police investigation-phase to sift through a database to find behaviorally similar cases to the one under investigation and in the trial-phase to try to prove that the perpetrator of two or more offences is the same, by showing similarity and distinctiveness in the offences. Lately, resea...

The recommendations of this white paper are jointly drafted by researchers in childinterviewing active within the European Association of Psychology and Law and are focusedon cases in which children are interviewed in forensic settings, in particular withininvestigations of child sexual and/or physical abuse.

Behavioural crime linking refers to the practice of trying to tie two or more offences to the same offender using behaviour observable at the crime scene. It rests on the assumptions that offenders behave consistently enough from one offence to another, and distinctively enough from other offenders allowing offences to be successfully linked togeth...

Child sexual abuse (CSA) evokes strong emotions and draws much media attention. In December 2018 through April 2019, there was a pre-election media frenzy in Finland around the topics of CSA and immigration. Some claimed there has been a significant increase in CSA cases, especially cases perpetrated by immigrants, while others maintained the headl...

Purpose To conduct a test of the principles underpinning crime linkage (behavioural consistency and distinctiveness) with a sample more closely reflecting the volume and nature of sexual crimes with which practitioners work, and to assess whether solved series are characterized by greater behavioural similarity than unsolved series. Method A sampl...

The objective of the study was to develop the methodology of behavioral crime linkage towards an applicable tool for the police to be used in homicide investigations. Thus far behavioral crime linkage studies on homicide have used datasets consisting exclusively of serial homicides. The present study, therefore, included hard-to-solve one-off offen...

The aims of this study were twofold: First, to describe a comprehensive assessment model utilized in a center specializing in child sexual abuse (CSA) investigations, and second, to describe the nature and characteristics of the families and allegations assessed, and analyze how case characteristics are related to the assessment outcomes of the CSA...

In Finland, specialised university hospital units have been set up to ensure a child-friendly and expert setting for investigating suspected crimes against children. The units conduct investigative interviews especially in cases involving young children or particularly vulnerable child victims, and provide expert assistance when requested by the po...

Purpose: This study compared the utility of different statistical methods in differentiating sexual crimes committed by the same person from sexual crimes committed by different persons. Methods: Logistic regression, iterative classification tree (ICT), and Bayesian analysis were applied to a dataset of 3,364 solved, unsolved, serial, and apparent...

Purpose – The purpose of this paper is to explore the differences (if any) between serial and hard-to-solve one-off homicides, and to determine if it is possible to distinguish the two types of homicides based on offence behaviours and victim characteristics. Design/methodology/approach – A sample of 116 Italian serial homicides was compared to 45...

This study explored whether a coding bias due to knowledge of which crimes have been committed by the same offender exists when behavioural variables are coded in serial murder cases. The study used an experimental approach where the information given to the participants (N = 60) concerning correct linkages between a number of murder series was man...

Esityksessä käydään läpi ajankohtaiset suositukset hyväksikäyttöepäilyjen tutkimiselle ja millä tavalla psykologin työskentely rikoksen esitutkinnassa erooa muista psykologin tekemistä tutkimuksista. Tuodaan esille miten selvittämisprosessissa keskeistä on tieteellinen ajattelu sekä hypoteesien (vaihtoehtoisten selitysten) muodostaminen ja testaami...

The Forensic Psychiatry Centre for children and adolescents at the Helsinki University Hospital conducts assessments of allegations of child sexual abuse at the request of the Police. In Finland, the Police investigate most such allegations. However, in cases where the children are pre-school age; or the allegation is particularly complicated and t...

The majority of child sexual abuse (CSA) allegations in Finland are investigated by the police. A select amount of the investigations are asked by the police to be conducted in five forensic psychiatry units for children and adolescents, which are part of university hospitals. Currently there is no research on the characteristics of the cases inves...

The present study aimed to identify dimensions of variation in serial homicide and to use these dimensions to behaviourally link offences committed by the same offender with each other. The sample consisted of 116 Italian homicides committed by 23 individual offenders. Each offender had committed at least two homicides. As some offenders had worked...

Method ResultsDiscussionReferences

The aim of the study was to identify offending types in a sample of difficult-to-solve Finnish homicides and to associate these offending types with situational variables and offender characteristics. The rationale for choosing such a group of cases was that it is in these cases that offender profiling is most likely to be applied and therefore the...

The aim of the study was to identify offending types in a sample of difficult-to-solve Finnish homicides. The rationale for choosing such a group of cases was that it is in these cases that offender profiling is most likely to be applied wherefore the statistical models should also be produced using these cases. All cases of homicide that occurred...