When electronic recording and transfer of information takes place, there are no traces left which would make it possible to identify the person recording or transferring information. Even if it is possible to identify the device - i.e. the computer used for the transfer, but not always the actual user. Computers guarantee almost total anonymity. A potential deceiver may take advantage of the situation and burden an innocent person operating the computer with illegal activities of the former. Such cases seriously disrupt the operation of the institutions using electronic transfer technology, particularly banks.

The only link between a human being and an electronic document is the memory trace. It can be examined by means of a polygraph, popularly known as a "lie detector". Polygraph tests can be used to prove that a given computer was operated by another person than the authorised one. The author presents an example illustrating the use of the polygraph. A second example shows that the traditional investigative techniques used by the police can be time-consuming, may violate personal rights of many people, or involve the exposure of confidential bank information.

Even though polygraph tests do not always result in the recovery of money or in punishing the perpetrator, they have other positive effects: innocent people are not at risk of losing their jobs, potential suspects are exonerated and employees regain the trust of the management.

Even "traditional" theft is unusual in banks and it is hardly ever done just for money. Usually people succumb to such temptations in situations when they are sure that the actual perpetrator will never fall under suspicion. Therefore, such cases require different approach and investigating methods. Polygraph tests are the optimal investigation technique here, particularly in the case of people who have been wrongly accused. The above advantages of polygraph tests have been recognised by the authors of the amendment to the Polish Criminal Code, which now allows the use of polygraph tests to reduce the number of potential suspects or, in other words, to exclude those wrongly accused. From the ethical point of view, the use of lie detectors is justified because actual perpetrator charges an innocent person with legal and civil liability and causes harm to his colleagues, to the company and its customers.