Forensic Psychology Cases


Forensic psychology is considered to be the branch dealing with law and psychology. This intersection between the criminal justice system and psychological sciences is aimed at the reformulation of psychological findings to make them understandable in the court. The history of forensic psychology presents a great number of cases related to this field, which help to identify the close connection between criminology and psychology. Several important factors are underlining tense interconnection between these two fields: criminal responsibility assessment, testifying, evaluation of competency, and recommendations to testimony. The cases ‘Jeffrey Dahmer Trial’ and ‘Bigby v. Dretke’ can serve as a bright illustration of forensic psychology’s role, impacting the verdict of the trial, regardless of the testimony provided by other witnesses.

The Trial of Jeffrey Dahmer

The first case to be analyzed in terms of its relation to forensic psychology is the trial of Jeffrey Dahmer, which took place in 1992. Jeffrey Dahmer was accused of killing 17 men for 10 years. This is an unusual case dealing with the strong psychological disorder of the killer. The man cannibalized some of the bodies, and some of them were turned into ‘zombies’.

The trial was directed at determining whether the killer could have been absolved of bearing responsibility for committed crimes because of insanity. As a result, the jury was provided with two different defendants’ characterizations. The first point was concentrated on the position that Jeffrey Dahmer was not a cruel man, but just a victim of personal sickness. Nevertheless, there was a contrary opinion, stating that he was guiltofor all the crimes for him being completely aware of everything he had done. The trial introduced experts’ testimony from both sides, involving the participation of psychologists and psychiatrists.

According to the defense experts, Dahmer was diagnosed with necrophilia, or abnormal sexual behavior, stressing that sexual urges lead to mass murder committed by the killer. The killer’s ‘overpowering’ caused insufficient ‘substantial capacity’ in personal actions control. According to the diagnosis, prescribed by Dr. Berlin, Dahmer felt his destiny in killing the men and cannibalizing them. Being erotically aroused by dead male bodies he felt miserable and despairing. It is necessary to stress the words of Dr. Berlin, saying that ‘I did not feel uncomfortable defending the position that an individual who recurrently experiences much more powerful urges to have sex with a corpse than with a living human being is an individual who is afflicted with a mental disease or defect’ (Fulero, and Wrightsman, 2008, p. 119) According to the second expert of defense side, Dr. Becker, Dahmer was diagnosed as having ‘psychotic-like behavior. Besides, it should be stressed that the killer was characterized as a sick man trying to avoid abandonment through committing murders.

According to the testimony presented by the prosecution side, the killer was not characterized by brutality and sadism, though he had complete control over his behavior and sexual desires. Dr. Dietz, who was a specialist in forensic psychology, stressed Dahmer’s capacity of methodical control over the behavior explaining it by his premeditation and sanity. The diagnosis of the specialist appeared to be the most effective and successful; he notified that Dahmer was not ill, but had the symptoms of total alcohol dependence and paraphilia, which means that he had sexual deviation.

The case under analysis underlines the function of forensic psychology as the key element in expert witnesses. Both sides the defense and the prosecution managed to witness as experts in forensic psychology, expressing their grounds for a taken position based on scientific investigations. The trial resulted in the jury decision either to recognize Dahmer’s mental disorder or his behavior control over committed actions explained by alcohol abuse.

Forensic psychology plaid a crucial role in trial results; the killer’s premeditation and sanity spoke of his awareness of committed murders and kept him close to reality. Dahmer was sentenced to life imprisonment in a high-security colony.

The case demonstrated a close connection between criminal justice and psychological interference. Conflicting conclusions connected with the testimony of both parts without forensic experts’ participation can lead to false and mistakable verdicts.

Bigby v. Dretke

The case Bigby v. Dretke, which took place in Texas, was related to mitigating evidence as a part of sentencing through forensic psychology testimony. It is necessary to underline the fact that according to forensic specialists, Michael Trekell and his son, who was found dead, appeared to be the victims of homicide. The defendant of the murder was James Bigby, who was the last person to be with victims before their deaths. The case was heard by the US District Court of Texas; the insanity defense was used by Bigby, presenting the testimony of several specialists, who diagnosed his mental disorders, such as paranoid schizophrenia and paranoid delusions, which made him commit the crime. Nevertheless, the trial resulted in Bigby’s insanity defense rejection based on expertise presented by forensic psychologists.

The death penalty verdict passed by the jury was struck by the court based on the medical and psychological history of the defendant, and taking into account mitigating factors. Mental disorders of the defendant appeared to be mitigating factors in case of death penalty sentencing, even taking into account the fact that this illness provided no impact on the initial results of the trial.

The case Bigby v. Dretke is characterized by the factors that mental illness can be presented in the form of sentence mitigation, even if they do not meet the insanity defense criteria. It is necessary to underline the fact that the report and evaluation conducted by forensic specialists in such cases are of considerable importance for sentence mitigation evidence. Taking into account the fact that the defendant has not all the symptoms of a mentally ill person, his state at the time of murder committing can be regarded as mitigation factors. (Romeo, 2006)


The analysis of two cases ‘Jeffrey Dahmer Trial’ and ‘Bigby v. Dretke’ has underlined the main task of forensic psychology, which is directed at individual’s mental state determination in the court for the jury to pass the verdict. Insanity as a legal concept appeared to be frequently used by forensic psychologists. The thing is that this notion has different interpretations in the system of jurisdiction that is why it caused some difficulties in diagnosing Dahmer’s state of mind. The assessment of competency is considered to be also an important task of forensic psychology, identifying the person’s ability to perceive the court proceedings’ purpose correctly. It impacts the decision of the jury, depending on the effectiveness of available assessment tools. It becomes clear that there are the following basic groups of issues referred to in competency evaluation: 1) the necessity to understand the trials and charges; 2) data relevance appreciation for a defense; 3) choice evidencing; and 4) decision making reasoning and abilities to provide logical problem-solving.

Forensic psychology provides strong assistance to the criminal system in criminal mitigation evaluation; the example of the ‘Bigby v. Dretke’ case investigated the presence of mitigation issues impacting the result of the trial when the guilt of the defendant was totally clear. It should be noted that death sentencing cases frequently stick to this method in the criminal justice system, explaining it by the fact that a person cannot commit so cruel crimes being in a state of complete control and awareness. Legal and moral tradition says that the person being unaware of the acts he performs cannot be responsible for them. It should be noted that the legal system centralizes the notion of ‘guilty mind’, stressing that a person can bear responsibility for the crime in case he had the intention to do it. That is why every conflicting case requires the interference of specialists in the sphere of forensic psychology. In case the defendant is recognized to be not criminally responsible for the crime, is usually judged as not guilty through ‘insanity reason’. (Fulero and Wrightsman, 2008)

There is a need to stress the importance of forensic psychology practice in criminal trials investigated above. The specialists of this field view and diagnose the defendants following the criteria differing from clinical psychologists. Forensic evaluations are focused on the assessment of factual information consistency through multiple sources. Every conclusion made by the forensic expert should be based on a particular source. Most courts order the assessment reports to be made by forensic psychologists; in such cases, the defendant is always notified about this decision. The principal task of forensic experts is aimed at recognizing faker and exaggerated symptoms of the defendant. (Bartol and Bartol, 2005)

The cases ‘Jeffrey Dahmer Trial’ and ‘Bigby v. Dretke’ were based on the conclusions of provided forensic psychology assessment reports. The experts performed several vital tasks in the process of cases investigation, impacting the final verdict. The testimony provided in the courtroom by psychologists, plaid a crucial role in passing a verdict. It should be noted that psychology testimony is one of the most difficult, presupposing the client’s evaluation based on law firm grasp and Crime Classification Manual. Specialists should have profound knowledge of the case, the client’s health history, and examination of the mental and psychological status of the defendant, as well as police reports and prior psychiatric evaluations. All these factors combined result insufficient evaluation of the defendant’s state of mind while committing the crime. (Romeo, 2006)


Forensic psychology is considered to be an integral part of the modern criminal justice system. The experts of this field have deep knowledge of the philosophy, standards, and regulations of both psychology and the criminal justice system. ‘Jeffrey Dahmer Trial’ and ‘Bigby v. Dretke’ underlined strong interference of forensic psychology with court trials, impacting passing a verdict in conflicting and complicated criminal cases. The cases analysis proved the crucial role of the science in criminal responsibility assessment, testifying, evaluation of competency, and recommendations to testimony. Tense interconnection between psychology and criminology leads to effective testimony and perfect functioning of the modern system of justice.


Bartol, C. and Bartol, A. (2005). Current Perspectives in Forensic Psychology and Criminal Justice. SAGE.

Fulero, S. and Wrightsman, L. (2008). Forensic Psychology. 3rd Edition, Cengage Learning, 476 pp.

Romeo, A. (2006). Mitigating Factors in the Death Penalty. Web.

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