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The Importance of Corroboration Within a Confession

April 2003 (click here for printable version)

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April, 2003

The Importance of Corroboration Within a Confession

Within the last year numerous inmates have been released from prison and had their convictions overturned as the result of post-trial exculpatory evidence. Many of these individuals confessed to the police. In some cases, the false confession was admitted as evidence. In other cases, the false confession was used as leverage to urge the suspect to accept a plea bargain, resulting in no trial..

The reported interrogations of some of these suspects involved physical coercion, duress and outright torture. While the Supreme Court has consistently prohibited such interrogation practices, evidently the trial courts rejected the defendant's claim that their confession was false. Traditionally, courts have afforded greater credibility to an investigator's testimony than that of a defendant anxious to escape punishment. However, because future defense claims of improper interrogation practices may be given more credence, investigators and prosecutors should anticipate greater scrutiny by the courts in admitting confession evidence. The once accepted axiom that no innocent person would confess to a crime has proven to be false. Because of this, the prosecution must demonstrate that a confession is, in fact, trustworthy. The most convincing evidence to demonstrate the truthfulness of a confession is corroboration.

Dependent Corroboration

At the outset of any investigation, the lead investigator should decide what evidence or information will be withheld from the public and all suspects for the purpose of verifying any subsequence confession. This is called dependent corroboration because the information is dependent upon the crime scene or other investigative source. In theory, only the person guilty of committing the crime should be able to provide this dependent corroboration.

The information selected for dependent corroboration needs to be carefully selected. Three guidelines can be offered in this regard:

1. The guilty person should reasonably remember the information

2. The information should not be so vital as to inhibit the investigator's efforts to effectively interview a suspect without revealing the information

3. The information should be mundane and not easily guessed by an innocent suspect

Consider a case where a young girl was abducted from her bedroom, driven to a remote location, sexually assaulted and then killed. The cause of death was strangulation. In an effort to hide the body, the murderer dragged the body about 50 feet to some underbrush and covered the body with tree branches. This scenario suggests many possible pieces of dependent corroboration. An investigator might select the victim's attire (pink pajamas) as dependent corroboration. However, a guilty suspect intent on committing the crime may not remember the color of the pajamas and an innocent suspect may guess that the victim was wearing pajamas. Another possible piece of dependent corroboration is the remote location where the body was found. However, withholding this information greatly restricts the investigator's ability to effectively interview the suspect. Perhaps the best piece of dependent corroboration in this case is the fact that the body was dragged to underbrush and covered with tree branches. Certainly the guilty person would remember doing this and withholding the information would not impair the interview of that person.

Defense attorneys will argue, sometimes with merit, that investigators inadvertently released dependent corroborative information to their client. We have personally encountered situations where an innocent person was able to provide such information because (1) crime scene photographs were used during an interrogation and (2) the information was revealed by an investigator who was not advised to keep the information secret. Especially in these times where an investigator's credibility may be suspect on the witness stand, dependent corroboration may not be viewed as definitive by a court or jury.

Independent Corroboration

Clearly the most convincing evidence of a truthful confession is one which contains verifiable information not known until the confession. This is called independent corroboration because the investigator does not know about the evidence until the suspect reveals it, and the evidence is obtained independent from the initial investigation. In the previous murder case, independent evidence would include such things as the tool used to gain entry to the victim's bedroom window (tool marks), a witness who could place the suspect near the crime scene (gas station attendant) or a souvenir kept from the victim (bracelet). Investigators tend to be reluctant to seek independent corroboration because they believe that it will only add time to an already lengthy investigation. However, the result of not spending this extra time is the possibility of having a guilty suspect's confession suppressed, or an innocent suspect convicted of a crime he did not commit.

Rational Corroboration

Consider that in our homicide example entry was made to the victim's bedroom through an open window, the suspect had a full tank of gas and kept no souvenir. Is there nothing left to possibly demonstrate the trustworthiness of the confession? The one other criteria courts may consider in deciding whether or not to admit a confession is whether it appears to be rational in its insight and detail.

A rational confession contains unsolicited thoughts and ideas in conjunction with specific behaviors that suggest spontaneous recollection of the crime. While an innocent person, with an active imagination, may be able to provide a rationale confession to someone else's crime, it is unlikely. As an example of a possibly false confession that lacks rational insight consider the following:

"On Saturday, January 15th I held up a man with a knife in an alley next to Bert's Tavern on Main Street. I stole this man's wallet and it contained $70 in cash. After I stole the wallet I pushed the man down and ran south on Main Street.

The reason the preceding confession should be viewed with suspicion is that it only verifies information already known to the investigator, and incorporates known patterns of behavior associated with street robberies. Compare the previous confession to the following (partial) confession that contains rationale insight statements:

"On Saturday, January 15th I was bored so I decided to rob a drunk guy leaving Bert's tavern. A guy who was probably 55 or 60 and obviously drunk left the tavern and when he approached an alley I asked him if he had a light for my cigarette. He went through his pockets for a lighter and at this point I pulled out a knife and said, 'come with me and give me your wallet.' I pushed him into the alley and took a wallet from him. I was afraid he might call the police on a cell phone so I told him, 'Give me your cell phone.' He said he didn't have one and I searched him and did not find one. At that point I ran south down main street and went to my apartment on Madison Street to count the money."

As illustrated, the first example covers all of the elements needed to prove the crime but the confession lacks insight or spontaneous behaviors. A confession is more likely to be considered trustworthy if it contains some of the following elements:

  • Quotations by the suspect or victim "Come with me and give me your wallet."
  • Thoughts or emotions "I was bored"
  • Explanations for behavior "I was afraid he might call the police"
  • Irrelevant details "A guy who was 55 or 60 and obviously drunk"


Conclusion

A confession is the most damaging possible evidence against a defendant in a court of law. However, as recent cases illustrate, innocent people can be coerced to offer or sign a false confession. The recent media attention focused on innocent persons being found guilty of a crime they did not commit should stimulate efforts by investigators to make certain that confessions obtained during the course of an investigation are, in fact, trustworthy. The best means to accomplish this goal is by corroborating the confession with (1) crime information that was withheld from the suspect, (2) information about the crime not known until the confession or, (3) rational information that reflects spontaneous recollection of the crime.

For further information on false confessions, and how to obtain a valid confession, see our book Criminal Interrogation and Confessions 4th edition

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