The Disease of Certainty

By Everett Doolittle, D.P.A.
Crime scene tape with two police officers and a police vehicle in the background. ©

I have had great opportunities over my many years in law enforcement. I have served as a police officer, a deputy sheriff, and even the chief deputy, but I found my greatest career opportunity at the Minnesota Bureau of Criminal Apprehension (BCA). At BCA, I tackled my most challenging assignment when I led the Cold Case Unit (CCU).

Early in my career, I gained valuable experience by working on homicide teams. But, studying the errors of others and reworking an old case granted me even greater insight into why cases fail. This article describes one of the major sources of these investigative errors: a phenomenon I dubbed the “Disease of Certainty.”

The Disease of Certainty is fatal to investigations. Both inexperienced and seasoned officers can catch this contagious disease, and it can spread throughout a team. It occurs when officers feel so convinced of their own beliefs that they allow themselves to become tunnel-visioned about one conclusion and ignore clues that might point them in another direction. Those who resist the disease may be ridiculed and ostracized for their supposed lack of understanding and inability to see the truth if all of their coworkers share the same beliefs and assumptions about the investigation.

The numerous cases that CCU worked over the years taught us many lessons about the Disease of Certainty. For clarification, when I refer to the BCA CCU, I include all members of the BCA team (agents, analysts, forensic scientists, and support personnel) and the local and county investigators who assist these investigations. Cold case investigations demand a multiagency approach to solve a difficult problem, so a diverse set of personnel with varying expertise comprise the team. 

By describing what I have learned about the Disease of Certainty, I do not aim to demean the work of the initial agencies involved, but to help others avoid the same mistakes in the future. I want to eliminate this deadly disease of perception that can prevent investigators from seeing beyond their own assumptions. All of these cases involved dedicated and professional individuals, but fatal errors occurred nonetheless. CCU does not aim to judge the initial investigators but to work with the agency as a team to reinvigorate the investigation. One person or agency never deserves all of the credit for cracking a case because it demands a true team effort.

A Case Study

Dr. Everett Doolittle
Dr. Doolittle retired from the Minnesota Bureau of Criminal Apprehension and currently serves as an associate professor in the School of Law Enforcement and Criminal Justice at Metropolitan State University in St. Paul, Minnesota. 

My work with CCU began with numerous rape and assault cases, but I will focus on a series of homicides. The first of the confirmed homicides occurred in December 1978. As the Huling family slept in their secluded rural farm house north of the Twin Cities (St. Paul and Minneapolis) in Minnesota, an intruder entered their home. Before leaving, the intruder viciously murdered Alice Huling and three of her children—miraculously, one survived. 

Several other seemingly unrelated crimes occurred over the following year. The next one took place in May 1979 when Marlys Wohlenhaus came home from school. A few hours later, her mother returned from errands and found Marlys severely beaten and unconscious. The girl was pronounced dead two days later. Next, in the following months, a young woman disappeared after leaving a restaurant. Though her car quickly was discovered near the Mississippi River, her body was not found for another five years. Yet again, soon after, a young girl left another restaurant where witnesses saw her forced into a vehicle, and her body was found days later.

These cases shocked the surrounding communities. However, because no apparent relationship existed between the crimes, the police departments investigated them individually. Several independent investigations continued for many years. In each of the cases, police identified a different prime suspect who became the central focus of the investigation.

The Disease Defined

To understand the seriousness of this issue, I need to explain the investigative process and how problems can arise. There are two logical approaches to problem solving that investigators must understand and use effectively: deductive and inductive reasoning. Deductive reasoning results from the evidence that people see in murder-mystery movies—the smoking gun, witnesses, DNA, fingerprints, and other tangible facts and clues. With deductive reasoning, this evidence builds the foundation of the case, and everything comes together to point to one conclusion.

Unfortunately, most real-life investigations differ greatly from the ones seen on television. In many cases, investigators can gather little if any tangible facts or evidence, which leads to a difficult, complex investigation that quickly can become a cold case. In these instances, investigators must turn to inductive reasoning to evaluate possible directions and outcomes. Through inductive reasoning, or scenario-based logic, we determine possibilities and probabilities based on experience and intuition and then attempt to prove or disprove them. Investigators start with a simple question, for example: Who killed Marlys Wohlenhaus? Could it be her boyfriend? What would be his motive? Could it be her stepfather or the neighbor kid who lives down the block? What would be their motives? Investigators attempt to identify possibilities and eliminate them one by one until only the most probable solution remains. To the seasoned investigator, this type of reasoning becomes the routine course of action.

These types of reasoning can go awry when in the mind of an investigator a possibility becomes the only reality. When officers become convinced of a certain solution, they may think that others who disagree with their answer simply do not understand. In most cases, experienced investigators’ instincts are correct, and their prime suspect indeed committed the crime. Nevertheless, one always must keep an open mind to the facts that disagree with an initial assessment as probability does not equate to certainty. Anyone can come to an incorrect first conclusion, especially when little or no straightforward evidence exists, and a conclusion is based mainly on conjecture.

The Case Resolved

In the serial murders outlined above, this Disease of Certainty led law enforcement personnel to disregard key information because it did not agree with their previous conclusions. However, when CCU reopened the case, many new hypotheses developed, and answers were found among the volumes of information the initial investigators had gathered. As in many cold cases, this only could happen when some initial investigators were removed and new personnel were assigned to support the case.

Eventually, CCU solved these crimes by examining a suspect who quickly had been cleared in the initial investigation. This man was not an acquaintance, stepfather, priest, or deputy, but a stranger. Joseph Ture was a drifter who lived in his car at a rest stop about four miles from the Huling home. Four days after the murders, police arrested Ture for an unrelated crime and found a ski mask, a club wrapped in leather, and a small toy car in his possession. These items became significant years later.

Two years later, in 1981, Ture was arrested and convicted of the murder of another waitress. While awaiting trial, he supposedly talked to his cellmate about his involvement in the murders of the Huling family and Marlys Wohlenhaus, and his statements were forwarded to law enforcement agencies. When officers questioned Ture, he maintained his innocence and claimed he was working at an automobile plant in St. Paul when the homicides occurred. The investigators contacted the plant and confirmed that a Joseph Ture was working on the assembly line at the time of the murder of Marlys Wohlenhaus. As a result, the officers eliminated Ture as a suspect.

When CCU personnel examined this case 20 years later, however, they reconsidered evidence, such as Ture’s statements to his cellmate and the items he possessed at the time of his initial arrest. They double-checked Ture’s alibi and realized that it actually was Joseph Ture, Sr., the suspect’s father, who worked at the automobile plant at the time of the murder. Upon further inquiry, CCU members discovered other incriminating remarks that the suspect made to his cellmate. Ture divulged information that only someone with direct involvement in the crime would have known. Also, the team found that Billy Huling, the one surviving child of the Huling home, could identify the toy car found with Ture when he was arrested decades earlier; Billy and his brother, Wayne, had played with a similar one prior to the night their family was murdered.

This example illustrates how investigators can become too convinced of their own conclusions. Because Joseph Ture allegedly was working at the time of the Wohlenhaus murder, officers disregarded other significant evidence against him. Once CCU reexamined previously held truths about the case (such as Ture’s alibi), they solved the crimes. This case has appeared numerous times on television.

Dangers of Overconfidence

Over the years, I have seen priests, deputy sheriffs, stepfathers, neighborhood kids, boyfriends, parents, spouses, and other innocent suspects become not only the focus of the investigation but the only possible answer in the minds of investigators. Once investigators develop this mind-set, it takes courage for others to stand up and disagree with the one perceived truth.

Also, this Disease of Certainty seriously can damage innocent individuals who mistakenly become the focus of the investigation. In some instances, little or no factual evidence exists against a suspect, yet the police, community, and media all believe the individual committed the crime. Rather than grieving the loss of a friend, acquaintance, or loved one, the suspect must deal with being viewed as a criminal in the eyes of the public.

Investigators face the challenge of pursuing their work confidently and proactively, yet understanding that they can be wrong and that if they are their errors impact many people. In this way, officers hold much power and influence over the lives of others, and their ethics matter a great deal. Police may want to solve cases quickly by relying on their instincts and investigating aggressively, but they also have a duty to remain open-minded, fair, and thorough. Working cold cases, I have seen the conflicts that arise when these priorities fall out of balance.

CCU’s success in identifying Ture as the murderer in no way detracts from the competency of the original investigators. But, to combat the Disease of Certainty, agencies must remember that personnel assigned to a particular case do not “own” that investigation. In the serial murders described above, the initial investigative teams included experienced officers who had long records of success, yet their experience may have contributed to their failures. These errors, while understandable, may not have occurred had the investigators not formed such strong beliefs of who committed the crimes. Experienced investigators draw on their past successes, which may blind them to unexpected possibilities.

A Wide Perspective

Many of the cases worked by CCU, like the Wohlenhaus and Huling murders, involved talented and dedicated personnel who focused too narrowly on one hypothetical conclusion. One incorrect hypothesis should not jeopardize an entire case. Every investigation reveals several paths that can lead in any number of directions, and, if it dead-ends, investigators need to turn around and try a new one. Problems arise, however, when police venture down the wrong path and refuse to see that they are going in the wrong direction.

Once investigators develop this fixed mind-set, they filter out information that disagrees with their conclusion and only see the evidence that supports their answers. I have observed this phenomenon often while managing multiagency task forces and referred to it as the “Don Quixote Effect.” Don Quixote, a famous literary hero, mistakenly battled windmills because he believed so strongly that they were giants. This idea resonates in Thomas Kuhn’s 1962 book, The Structure of Scientific Revolutions, which discusses the difficulties experienced by scientists when they discovered information that disagreed with their long-held truths or paradigms.

Overconfidence is not the only way that the Disease of Certainty can infiltrate an investigation. Sometimes, a lack of perspective leads the team awry. When investigators dig deeply into the facts of a case, they can become too focused on one suspect, one lead, or one piece of information and lose sight of the bigger picture. This line of thinking caused investigators to mistakenly eliminate Joseph Ture as a suspect in the crimes described above.

When venturing into a densely wooded forest—it is easy to lose sight of the forest when surrounded by trees. Similarly, when officers become bogged down by puzzling information and unanswered questions, they may find it difficult to see the bigger picture of the case. Solving a difficult and complex investigation with keen inductive reasoning demands more than a team of dedicated personnel; it requires a leader. True leaders can see beyond disparate facts and seemingly unrelated evidence to view the whole “forest,” and they have the courage to tell others when they are heading in the wrong direction.


Because the Cold Case Unit receives cases after a significant amount of time has passed and all initial leads have been exhausted, it brings a fresh perspective to the puzzle. CCU’s investigators are not the same team of officers who responded to the scene of the crime, interviewed witnesses, interacted with a grieving family, and felt the pressure of media attention that surrounds high-profile cases; because of this, they may provide a new approach missing from the initial investigation.

Additionally, because CCU receives cases that stumped a dedicated team of investigators, cold case officers know they must consider “out-of-the-box” solutions and, thus, are less susceptible to the Disease of Certainty. A unit, such as ours at BCA, can provide this service for any agency willing to challenge experienced investigators’ long-held beliefs and dig into old cases. Agencies must remember that even their most talented officers can fall victim to overconfidence, and this Disease of Certainty may have caused errors in cold cases that still can be resolved.






















“Both inexperienced and seasoned officers can catch this contagious disease, and it can spread
throughout a team.”