How evidence is collected in Poisoning cases? Examination of Poison cases in forensics

Have you ever wondered what kind of samples; these doctors collect in order to detect the type of poison from the victim. The samples are heavily depend upon


Shubham Kumar

1/29/20246 min read

In the cases of poisoning, the victim must hospitalize immediately, and he must be diagnosed with proper arrangements to detect the type of poison. In most of the poisoning cases, doctors detect the type of poison, in some cases doctors detect the type of poisoning at first glance, and in some cases, they run some tests. Furthermore, this gives us the idea that, analysis of the body reveals the root of problems within it. However, have you ever wondered what kind of samples; these doctors collect in order to detect the type of poison?

In this article we are going to learn about the types of biological samples required by the doctors to detect the poison from the victim.

Whenever a doctor has to diagnose a victim for the detection of poison, then the sample collection totally depends upon the state of the victim, whether a victim is alive or dead. Furthermore, the samples to be collected in case of alive victim differs than that of samples to be collected in case of dead victim.

Moreover, the precautions for the degrading of samples, are exerts more on deceased victim. Notably, the analysis of these samples are done by forensic toxicologists, which comes under the science of Forensic Toxicology. Therefore, if you want to learn more about forensic toxicology you can visit: Forensic Toxicology | All you need to Know! | Or you can simply visit on Forensic Toxicology - Page - It's Forensic ( Moreover, I strongly recommend you to first learn about what exactly a poison is, so visit this Poison | Everything you need to know about it!, before reading forward.

Appropriate materials for detection of poison from the victim in survival cases | When the victim is alive.

When the victim is alive, the topmost priority of the doctors is to protect the victim and save his life from death. Simultaneously, the proper collection and analysis of his bodily samples are also listed in priority list. The samples which are to be collected when victim is alive are listed below.

Urine | Best in Poison Detection

Urine is regarded as the best specimen for the determination of type of poison, from which the victim is suffering. Moreover, doctors usually prefer urine analysis for the detection of potential drugs and poisons present inside the victim. The urine should be collected as much as possible, usually collection of 30ml is advised.

Urine is regarded as the best specimen because, urine is collectively the sum of all impurities in body. Moreover, the accumulation of drugs, poisons, and metabolites in urine will often results in high concentration that facilitates their detection.

The urine sample should be collected in plain sterile plastic container, avoiding the use of boric acid containers. If the victim is unconscious, then the urine can be collected by direct puncture of the exposed bladder. An instrument called urethral catheter is used to collect the urine, inserting into the exposed bladder.

Blood | Best in Quantifying Poison

Indeed, urine is one of the best specimens for detection of poison, however, when it comes to determine the quality and quantity of poison, nothing can match blood. The analysis of blood helps in quantifying and interpreting the concentration of poison in body. Moreover, the metabolite in blood also provides information regarding the drugs and alcohol concentration.

The doctors are advised to collect at least 10ml of blood and add 100gm sodium fluoride, so as to preserve the blood, moreover, it also act as anticoagulant.

Notably, in the suspected cases of poisoning from fluoride materials, then instead of sodium benzoate, EDTA (Ethylenediamine Tetra Acetic Acid) is used as preservative and anticoagulant.

Notably, it is advised to collect the blood from the femoral and peripheral vein. In order to detect the poison, the femoral vein is used, whereas to detect the alcohol, peripheral vein is used. Notably, methanol is a type of alcohol, however, it act as poison, therefore, doctors are advised to collect blood from both the veins in case of poison.

Moreover, it is important not to mix blood samples from different sites, as variations in drug concentration can occur based on the collection time after death, sampling site, method, and volume.  


Vomit and stomach wash both shares common interests and common reasons for their collection. However, unlike stomach wash, vomit is a natural process and involuntary act of throwing the stomach's content through mouth. Moreover, it is a natural reflex that a body does in order to get rid of harmful substances present in stomach. Vomit usually indicated the food poisoning, ingestion of intoxicants, and excessive alcoholism.

Stomach Wash | Best in Determining impact of Poison in internal organs

One of the most common route of administration of poison is oral route. The poisonous substance is completely swallowed and then absorbed by the mucus wall in digestive tracts. Poison taken from this route directly affects GIT, the upper respiratory tract, stomach, and other organs. Therefore, the stomach wash is collected in order to detect the poison. Moreover, stomach wash helps in determining the impact of poison on internal organs. Stomach wash is usually done when the victim is not vomiting, therefore, to analyze the stomach content gastric lavage is performed. A long tube is inserted from victim's nose or mouth, then the stomach is washed with a saline water, after washing, the content is suction out from the body. Stomach wash of gastric lavage is done to remove the toxic substance from stomach before it gets absorbed by the body.

Gastric lavage is performed when the victim as consumed poison by oral route and consumed only recently.

Feces Material

Feces materials are analyzed, because it is covered with the mucus for their smooth bowel movements. The mucus layer is analyzed to detect the impact of poison.

Suspected Materials from Crime Scene | Provides deep insights about potential used poisons

On crime scene investigation, the suspected materials like empty medicine vials, remaining food and drinks, residual poisons, vomits, strips of capsules and poisons, etc, plays important role in early detection of poison.

Appropriate materials for detection of poison from the victim in fatal cases | When the victim is dead.

When the victim is dead, then doctors should hurry to collect all the required samples because they are already running out of time. Notably, the process like autolysis, and putrefactive actions that occurs after death, have profound effect on the concentration of poison, that are present in the body after death. Moreover, the postmortem redistribution acts as catalysts in all these degrading processes. The sample which a doctor collects when the victim is dead is called viscera. The viscera is the trump card in determination of poison in the body. Viscera is collected during autopsy.


The viscera refer to the recovery of the internal organs from a deceased body for further analysis. These internal organs are divided into thoracic, abdominal, genital and cranial viscera. These organs encompass a range of vital structures, including the heart, lungs, liver, spleen, kidneys, stomach, intestines, and bladder, among others.

The selection of viscera sample depends upon the type of poison used and the potential distribution of poison in the internal organs. The selection of viscera sample for chemical analysis is very crucial in legal investigations. Ideally, the decision of take viscera sample for analysis should be made before the conduction of postmortem, by examination of medical report, police report, death report and treatment report.

Wide mouth glass or plastic bottle with 2L capacity with airtight container should be used for collection of viscera. Moreover, each sample, should be well labeled with full name of deceased, specimen type, collection site, date/time of collection, and initials of the individuals collecting the sample.

Visceral Sample

  • Stomach or whole stomach content or stomach wash, which ever is available.

  • Proximal parts of small intestine along with its contents.

  • 100 gm of liver in pieces. The portion containing the gall bladder and its content is often preferred.

  • Half of each Kidney is collected

  • Blood should be collected about 50ml. The blood should be collected via femoral vein or artery with a wide bore needle via percutaneous puncture. However, its never advisable to collect the blood from open or spilled area.

  • Spleen is collected. Half of spleen in adult and whole spleen in children.

  • 100ml of urine or the present amount of urine available in bladder should be collected. Urine can be collected by direct puncture of the exposed bladder. An instrument called urethral catheter is used to collect the urine, inserting into the exposed bladder before the autopsy.

However, these are not all the visceral sample, these sample are collected only in cases of poison. If you want to know more about viscera or visceral sample, you can check out- Viscera | All you need to know about it!

These were all the sample, which a doctor use to detect the poison from the victim. I hope this post has achieved its aim to make you understand about the samples required by doctors to detect the poison from victim.


  • "Forensic DNA Typing" by John M. Butler

  • "The Forensic Casebook: The Science of Crime Scene Investigation" by Ngaire E. Genge

  • "Forensic Science: A Very Short Introduction" by Jim Fraser

  • "Practical Crime Scene Processing and Investigation" by Ross M. Gardner