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4.4: Collecting Evidence

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    Before we can begin the criminal court process, we must have a criminal investigation to collect evidence of guilt. In this module, we will look at the role the police/law enforcement plays in collecting evidence for presentation in the trial. As we progress in this course, you will see how vital it is that officers understand the rights of suspects and the importance of following criminal court processes and procedures. If an officer fails to properly collect evidence, that evidence could be excluded from the court and a guilty person could go free. Or evidence could be falsely obtained and an innocent person could be found guilty. This is one of the worst things that could occur because our country was founded on specific principles to ensure all citizens are treated fairly and just in the criminal court.

    Pin It! Crime Scene Investigation and Evidence Collection

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    In this module, we will look at some of the key definitions and protocols that an investigator should understand to carry out the investigative process:

    • The probative value of the evidence
    • Relevant evidence
    • Direct evidence
    • Circumstantial evidence
    • Inculpatory evidence
    • Exculpatory evidence
    • Corroborative evidence
    • Disclosure of evidence
    • Witness evidence
    • Hearsay evidence
    • Search and seizure of evidence
    • Exclusion of evidence

    The Probative Value of Evidence

    Each piece of relevant evidence will be considered based on its “probative value,” which is the weight or persuasive value that the court assigns to that particular piece of evidence when considering its value towards proving a point of fact in question for the case being heard. This probative value of evidence goes towards the judge, or the judge and jury, reaching their decision of proof beyond a reasonable doubt in criminal court, or proof within a balance of probabilities in civil court.

    Eyewitness Evidence

    A competent, compellable, independent, eye witness with excellent physical and mental capabilities, who has seen the criminal event take place and can recount the facts will generally satisfy the court and provide evidence that has high probative value. In assessing the probative value of witness evidence, the court will consider several factors that we will discuss in more detail in our chapter on witness management. These include:

    • The witness type as either eyewitness or corroborative witness.
    • The witness competency to testify.
    • The witness compellability to testify.
    • The level of witness independence from the event.
    • The witness credibility is based on an assessment of physical limitations.

    Physical Evidence

    The court will also generally attribute a high probative value to physical exhibits. The court likes physical evidence because they are items the court can see and examine to interpret the facts in issue for proof beyond a reasonable doubt. Physical evidence can include just about anything, such as weapons, fingerprints, shoe prints, tire marks, tool impression, hair, fiber, or body fluids. These kinds of physical exhibits of evidence can be examined and analyzed by experts who can provide the court with expert opinions that connect the item of evidence to a person, place, or criminal event. This allows the court to consider circumstantial connections of the accused to the crime scene or the accused to the victim. For example, in the case where the fingerprints of a suspect are found at a crime scene, and a DNA match of a murder victim’s blood is found on that suspect’s clothing, forensic connections could be made and, in the absence of an explanation, the court would likely find this physical evidence to be relevant and compelling evidence with high probative value.

    Relevant Evidence

    Relevant evidence speaks to an issue before the court in relation to the charge being heard. Relevant evidence includes both direct evidence and indirect circumstantial evidence. For either direct or indirect circumstantial evidence to be considered relevant to the court, it must relate to the elements of the offense that need to be proven. If the evidence does not relate to proving the place, time, identity of the accused, or criminal acts within the offense itself, the evidence will not be considered relevant to the charge. The prosecution may present evidence in the form of a physical exhibit that the court can see and examine to consider, or they may present evidence in the form of witness testimony, in which case the witness is telling the court what they perceived within the limits of their senses.

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    Direct Evidence

    Direct evidence is evidence that will prove the point in fact without interpretation of circumstances. It is any evidence that can show the court that something occurred without the need for the judge to make inferences or assumptions to reach a conclusion. An eyewitness who saw the accused shoot a victim would be able to provide direct evidence. Similarly, a security camera showing the accused committing a crime or a statement of confession from the accused admitting to the crime could also be considered direct evidence. Direct evidence should not be confused with the concept of direct examination, which is the initial examination and questioning of a witness at trial by the party who called that witness. And, although each witness who provides evidence could, in theory, be providing direct testimony of their own knowledge and experiences, that evidence is often not direct evidence of the offense itself.

    Circumstantial Evidence

    Indirect evidence, also called circumstantial evidence, is all other evidence, such as the fingerprint of an accused found at the crime scene. Indirect evidence does not by itself prove the offense, but through interpretation of the circumstances and in conjunction with other evidence may contribute to a body of evidence that could prove guilt beyond a reasonable doubt. Strong circumstantial evidence that only leads to one logical conclusion can sometimes become the evidence the court uses in reaching belief beyond a reasonable doubt to convict an accused. It requires assumptions and logical inferences to be made by the court to attribute meaning to the evidence.

    • Circumstantial evidence demonstrates the spatial relationships between suspects, victims, timelines, and the criminal event. These spatial relationships can sometimes demonstrate that an accused person had a combination of intent, motive, opportunity, and/or the means to commit the offense, which are all meaningful features of criminal conduct.
    • Circumstantial evidence of intent can sometimes be shown through indirect evidence of the suspect planning to commit the offense, and/or planning to escape and dispose of evidence after the offense. A pre-crime statement about the plan could demonstrate both intent and motive, such as, “I really need some money. I’m going to rob that bank tomorrow.”
    • Circumstantial evidence of conflict, vengeance, financial gain from the commission of the offense can also become evidence of motive.
    • Circumstantial evidence of opportunity can be illustrated by showing a suspect had access to a victim or a crime scene at the time of the criminal event, and this access provided the opportunity to commit the crime.
    • Circumstantial evidence of means can sometimes be demonstrated by showing the suspect had the physical capabilities and/or the tools or weapons to commit the offense.

    Presenting this kind of circumstantial evidence can assist the court in confirming assumptions and inferences to reach conclusions assigning probative value to connections between the accused and a person or a place and the physical evidence. These circumstantial connections can create the essential links between a suspect and the crime.

    There are many ways of making linkages to demonstrate circumstantial connections. These range from forensic analysis of fingerprints or DNA that connect an accused to the crime scene or victim, to witness evidence describing criminal conduct on the part of an accused before, during, or after the offense. The possibilities and variations of when or how circumstantial evidence will emerge are endless. It falls upon the investigator to consider the big picture of all the evidence and then analytically develop theories of how events may have happened. Once a reasonable theory has been formed, evidence of circumstantial connections can be validated through further investigation and analysis of physical exhibits to connect a suspect to the crime.

    Inculpatory Evidence

    Inculpatory evidence is any evidence that will directly or indirectly link an accused person to the offense being investigated. For an investigator, inculpatory evidence can be found in the victim’s complaint, physical evidence, witness accounts, or the circumstantial relationships that are examined, analyzed, and recorded during the investigative process. It can be anything from the direct evidence of an eyewitness who saw the accused committing the crime, to the circumstantial evidence of a fingerprint found in a location connecting the accused to the victim or the crime scene.

    Naturally, direct evidence that shows the accused committed the crime is the preferred inculpatory evidence, but, in practice, this it is frequently not available. The investigator must look for and interpret other sources for evidence and information. Often, many pieces of circumstantial evidence are required to build a case that allows the investigator to achieve reasonable grounds to believe and enables the court to reach their belief beyond a reasonable doubt.

    A single fingerprint found on the outside driver’s door of a stolen car would not be sufficient for the court to find an accused guilty of car theft. However, if you added witness evidence to show that the accused was seen near the car at the time it was stolen, and a security camera recording of the accused walking off the parking lot where the stolen car was dumped, and the police finding the accused leaving the dumpsite where he attempted to toss the keys of that stolen car into the bushes, the court would likely have proof beyond a reasonable doubt.

    If an abundance of inculpatory circumstantial evidence can be located for presentation to the court that leads to a single logical conclusion, the court will often reach their conclusion of proof beyond a reasonable doubt, unless exculpatory evidence is presented by the defense to create reasonable doubt.

    Exculpatory Evidence

    Exculpatory evidence is the exact opposite of inculpatory evidence in that it tends to show the accused person or the suspect did not commit the offense. It is important for an investigator to not only look for inculpatory evidence but also consider evidence from an exculpatory perspective. Considering evidence from the exculpatory perspective demonstrates that an investigator is being objective and is not falling into the trap of tunnel vision. If it is possible to find exculpatory evidence that shows the suspect is not responsible for the offense, it is helpful for police because it allows for the elimination of that suspect and the redirecting of the investigation to pursue the real perpetrator.

    Sometimes, exculpatory evidence will be presented by the defense at trial to show the accused was not involved in the offense or perhaps only involved to a lesser degree. In our previous circumstantial case of car theft, there is a strong circumstantial case; but what if the defense produces the following exculpatory evidence where:

    • A tow truck dispatcher testifies at the trial and produces records showing the accused is a tow truck driver;
    • On the date of the car theft, the accused was dispatched to the site of the car theft to assist a motorist locked out of his car;
    • The accused testifies that he only assisted another male to gain entry to the stolen car because he could see the car keys on the front seat;
    • The accused explains that, after opening the car, he agreed to meet this male at the parking lot where the car was left parked;
    • He accepted the keys of the stolen car from the other male to tow the vehicle later to a service station from that location;
    • When approached by police, he stated that he became nervous and suspicious about the car he had just towed; and
    • He tried to throw the keys away because he has a previous criminal record and knew the police would not believe him.

    Provided with this kind of exculpatory evidence, the court might dismiss the case against the accused.

    Having read this, you may be thinking that this exculpatory evidence and defense sounds a little vague, which is the dilemma that often faces the court. If they can find guilt beyond a reasonable doubt, they will convict, but if the defense can present evidence that creates reasonable doubt, they will make a ruling of not guilty. Experienced criminals can be very masterful at coming up with alternate explanations of their involvement in criminal events, and it is sometimes helpful for investigators to consider if the fabrication of an alternate explanation will be possible. If an alternate explanation can be anticipated, additional investigation can sometimes challenge the untrue aspects of the alternate possibilities.

    Corroborative Evidence

    The term corroborative evidence essentially refers to any type of evidence that tends to support the meaning, validity, or truthfulness of another piece of evidence that has already been presented to the court. A piece of corroborative evidence may take the form of a physical item, such as a DNA sample from an accused matching the DNA found on a victim, thus corroborating a victim’s testimony. Corroborative evidence might also come from the statement of one independent witness providing testimony that matches the account of events described by another witness. If it can be shown that these two witnesses were separated and did not collaborate or hear each other’s account, their statements could be accepted by the court as mutually corroborative accounts of the same event.

    The courts assign a great deal of probative value to corroborative evidence because it assists the court in reaching their belief beyond a reasonable doubt. For investigators, it is important to not just look for the minimum amount of evidence apparent at the scene of a crime. The investigation must also seek out other evidence that can corroborate the facts attested to by witnesses or victims in their accounts of the event. An interesting example of corroborative evidence can be found in the court’s acceptance of a police investigator's notes as being circumstantially corroborative of that officer’s evidence and account of the events. When a police investigator testifies in court, they are usually given permission by the court to refer to their notes to refresh their memory and provide a full account of the events. If the investigator’s notes are detailed and accurate, the court can give significant weight to the officer’s account of those events. If the notes lack detail or are incomplete on significant points, the court may assign less value to the accuracy of the investigator’s account.

    For the court, detailed notes properly made at the time corroborate the officer’s evidence and represent a circumstantial guarantee of trustworthiness for the officer’s testimony (McRory, 2014).

    Disclosure of Evidence

    It is important for an investigator to be aware that all aspects of their investigation may become subject to disclosure as potential evidence for court. A person who's been formally accused of a crime is normally entitled to certain kinds of evidence, statements, and information. The defendant has a right to receive this kind of material, called "discovery" before trial, however; the prosecution or police's duty to relinquish discovery is normally ongoing throughout the trial process.

    The United States Constitution does require that the prosecution discloses to the defense exculpatory (minimizes guilt) evidence within its control. In 1963 the United States Supreme Court decided a case {Brady v. Maryland} in which the Court held that it's a violation of due process for the prosecution to suppress evidence that the defense has requested which is material to guilt or favorable to the accused. Brady has been codified in most states, meaning it is a violation of law for a prosecutor to intentionally withhold discovery.

    In the disclosure process, the decision to disclose or not to disclose is the exclusive domain of the prosecutor and, although police investigators may submit information and evidence to the prosecutor with the request that the information is considered an exception to the disclosure rules, the final decision is that of the Court. That said, even the decision of the Court may be challenged by the defense and that then becomes a final decision for the Judge. The prosecutor will ask the police to provide full disclosure of the evidence gathered during their investigation.

    The list of what should form part of a normal disclosure will typically include:

    • Charging document
    • Particulars of the offense
    • Witness statements
    • Audio/video evidence statements by witnesses
    • Statements by the accused
    • Accused’s criminal record
    • Expert witness reports
    • Notebooks and Police reports
    • Exhibits
    • Search warrants
    • Authorizations to intercept private communications
    • Similar fact evidence
    • Identification evidence
    • Witnesses’ criminal records
    • Reports to the Court recommending charges
    • Witness impeachment material

    It is worth stressing that police notes and reports relating to the investigation are typically studied very carefully by the defense to ensure they are complete and have been completely disclosed. Disclosure will also include investigation notes and reports that relate to alternate persons considered, investigated, and eliminated as suspects in the crime for which the accused is being tried. If alternate suspects were identified and not eliminated during the investigation, that lack of investigation may form the basis for a defense to the charge.

    For an investigator, the requirement to comply with disclosure is one of the best reasons to make sure notes and reports are complete and accurately reflect the investigation and actions taken during the investigation. From the court’s perspective, there will never be any excuse for a police investigator to intentionally conceal or fail to disclose evidence or information.

    Witness Evidence

    Witness evidence is evidence obtained from any person who may be able to provide the court with information that will assist in the adjudication of the charges being tried. This means that witnesses are not only persons found as victims of a crime or on-scene observers of the criminal event. They may also be persons who can inform the court on events leading up to the crime, or activities taking place after the crime.

    These after-the-crime activities do not just relate to the activities of the suspect, but also include the entire range of activities required to investigate the crime. Consequently, every police officer involved in the investigation, and every person involved in the handling, examination, and analysis of evidence to be presented in court, is a potential witness.

    Issues relating to the collection of witness evidence will be discussed in more detail in Chapter 7 on Witness Management.

    Hearsay Evidence

    Hearsay evidence, as the name implies, is evidence that a witness has heard as communication from another party. In addition to verbal communication, legal interpretations of the meaning of hearsay evidence also include other types of person-to-person communication, such as written statements or even gestures intended to convey a message.

    Pin It! Hearsay Evidence

    Learn more about what qualifies evidence as “hearsay evidence” and how it is handled in this video: hearsay evidence.

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    Hearsay evidence is generally considered to be inadmissible in court at the trial of an accused person for several reasons; however, there are exceptions where the court will consider accepting hearsay evidence. The reasons why hearsay is not openly accepted by the court include the rationale that:

    • The court generally applies the best-evidence rule to evidence being presented and the best evidence would come from the person who gives the firsthand account of events;
    • The original person who makes the communication that becomes hearsay is not available to be put under oath and cross-examined by the defense;
    • In hearing the evidence, the court does not have the opportunity to hear the communicator firsthand and assess their demeanor to gauge their credibility; and
    • The court recognizes that communication that has been heard and is being repeated is subject to interpretation. Restatement of what was heard can deteriorate the content of the message.

    The court will consider accepting hearsay evidence as an exception to the hearsay rule in cases where:

    • There is a dying declaration
    • A witness is the recipient of a spontaneous utterance
    • The witness is testifying to hearsay from a child witness who is not competent

    Dying Declarations

    Exceptions to the hearsay rule include the dying declaration of a homicide victim. This type of declaration is allowed since it is traditionally believed that a person facing imminent death would not lie. This is a delicate area because in cases where the victim of a serious assault is in danger of dying, the investigator may have the opportunity to gain evidence by taking a statement from that victim; however, that statement would need to include some acknowledgment by the victim that they believed they are in imminent danger of dying.


    This page titled 4.4: Collecting Evidence is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Tabitha Raber.

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