Only 2 pct. of innocent suspects can give watertight alibi: study

Police tape seals crime scene for forensic investigation
Police tape seals crime scene for forensic investigation. Photo: Zachary Newmark / NL Times

The Dutch police impose unrealistically high expectations on alibis, which can have serious consequences for innocent suspects, according to PhD research by criminal psychologist Ricardo Nieuwkamp of Maastricht University. Only 2 percent of innocent suspects are able to give the police an alibi that they will accept, the Volkskrant reports.

Nieuwkamp based his research on existing literature and interviews with hundreds of test persons, including laymen and detectives. He asked his test persons to prove where they were at the time of a fictitious robbery. Only a quarter were able to show where they were with, for example, debit card payments, mobile phone data and witness statements. 

But this type of evidence is not considered enough for the police. Because a suspect could have deliberately loaned his debit card, public transit card or cellphone to someone else - specifically to set up an alibi. Witness statements are also not considered hard evidence. A nighttime alibi is especially difficult to prove, because how do you prove you were sleeping in bed? A partner's statement is always suspect. 

Detectives only consider an alibi watertight if there is physical evidence, such as camera footage or evidence that you were on a flight where your passport was checked. Another condition is that suspects' stories must stay consistent, with no deviation what so ever. Only 30 percent of innocent suspects manage to keep their stories perfectly straight, according to Nieuwkamp.

Innocent suspects face a significant disadvantage when suddenly faced with the question: where were you on Wednesday evening two weeks ago?, Nieuwkamp says, according to the newspaper. "The stress of the interrogation has a negative effect on memory. With a bare date it is difficult to retrieve memories. If the suspect makes mistakes, the police quickly think that he is lying. Moreover, innocent suspects have no idea wat a good alibi is in the eyes of the police and have the naive idea that justice will prevail and that they will be believed. Unfortunately, that is not always the case."

Distinguishing fake alibis from real ones is also pretty difficult, Nieuwkamp found. He presented false and real alibis to 200 people, again laymen and detectives. They were able to find the fake ones in only 60 percent of the cases - little more than chance. "Thieves know only too well that the police like to see evidence. In Aalst, a suspect of murder managed to support his alibi with surveillance footage from the hotel where he was staying. He slipped unseen through a window on the ground floor to murder his wife and children."

Nieuwkamp hopes that his research will show the police how difficult it is for innocent suspects to prove their alibi and that detectives will be trained in the future to properly question suspects' alibis. The police refused to respond to Nieuwkamp's research to the Volkskrant, because they haven't read the report yet.