Oral Swab: A Key Source of Evidence for Forensic Identification

. Specific Applications

1. Individual Identification
   • In the forensic field, oral swabs are important tools for individual identification. When encountering unidentified corpses or needing to confirm the identity of criminal suspects, by collecting oral mucosal cells through oral swabs and extracting DNA from them, they can be compared with the DNA databases of known persons. For example, in some criminal cases, there are items with saliva left at the crime scene, such as cigarette butts and chewing gum. Forensic doctors can use oral swabs to collect cells from these items, obtain DNA information, and then match it with the DNA of criminal suspects to help determine the identity of criminal suspects. This method of identity recognition based on DNA analysis of oral swabs plays a key role in solving cases.
2. Identification of Disaster Victims
   • After a disaster event, such as an earthquake, air crash, or large – scale fire, identifying the victims is often a difficult task. Oral swabs play an important role in this process. Rescuers can collect samples from the oral cavities of victims, and by analyzing the DNA of these samples and comparing it with the DNA samples provided by family members, the identities of victims can be accurately confirmed. This method is more accurate and reliable than traditional methods relying on appearance characteristics or identifying by relics, can bring accurate information to the families of victims, and is also helpful for handling subsequent legal and insurance – related matters.
3. Evidence Collection in Sexual Assault Cases
   • In sexual assault cases, oral swabs are one of the important means of collecting evidence. For the body fluids or cells of criminal suspects that may exist in the oral cavity of victims, forensic doctors can use oral swabs to collect them. These samples, after testing, can be used as key evidence for determining the identity of criminal suspects and proving criminal facts. For example, in some cases of violent sexual assault, there may be semen or skin cells of criminal suspects remaining in the oral cavity of victims, and oral swabs can effectively collect these evidences to provide strong support for judicial trials.

II. Advantages

1. Easy Sample Acquisition
   • One of the significant advantages of oral swabs in forensic identification is the ease of sample acquisition. Compared with other methods that require surgery or complex operations to obtain samples, oral swabs only need simple operations in the oral cavity to obtain cell samples containing DNA. In various complex on – site environments, such as crime scenes or disaster scenes, as long as relevant items containing oral cells can be found, samples can be relatively easily collected, providing convenience for subsequent identification work.
2. Well – preserved DNA
   • The DNA in oral mucosal cells is relatively well – preserved under appropriate conditions. The samples collected by oral swabs can maintain a high degree of DNA integrity for analysis in suitable storage environments, even after a period of time. This is of great significance for some forensic cases that require long – term sample processing or storage, such as the reinvestigation of old cases.
3. Non – invasive to Avoid Ethical Controversies
   • The non – invasive operation of oral swabs avoids many ethical controversies. In forensic practice, especially when collecting samples from living individuals, non – invasive sampling methods are more easily accepted. Compared with blood – collection and other methods that may involve issues such as harming the living, violating privacy, and other ethical problems, oral swab sampling has advantages in respecting human rights and following ethical norms, and can reduce unnecessary ethical disputes while ensuring judicial justice.

III. Precautions

1. Legality of Samples
   • When using oral swabs to collect samples in forensic medicine, it is necessary to ensure the legality of the samples. When collecting samples from living individuals, strict legal procedures need to be followed, and legal authorization from relevant persons, such as the consent of criminal suspects or the approval of the court, needs to be obtained. For samples collected at crime scenes or disaster scenes, it is also necessary to ensure that the collection process complies with relevant legal regulations to ensure that the samples can be adopted as valid evidence in subsequent judicial procedures.
2. Prevention of Sample Contamination and Tampering
   • Oral swab samples need to prevent contamination and tampering during collection, storage, and transportation. During collection, disinfected and well – sealed swabs should be used to avoid foreign impurities mixing into the samples. During storage and transportation, strict security measures should be taken, such as using sealed containers and recording the circulation process of samples, to prevent samples from being tampered with or damaged by humans. Once there are problems such as sample contamination or tampering, the identification results may be invalid, affecting judicial justice.
3. Professional Operation and Result Interpretation
   • Both the collection of oral swabs and the subsequent DNA analysis require professional personnel to operate. Non – professional personnel may cause sample – collection failure or inaccurate DNA extraction due to improper operation. At the same time, the interpretation of DNA analysis results also requires professional knowledge and experience. In forensic identification, incorrect result interpretation may lead to misjudgment. Therefore, it must be operated and analyzed by forensic doctors or relevant technical personnel with professional qualifications.