A corpse with serious injures left lonely stretch on rare area from the city. A fire broke out at a lawyer office just one day before the court. A car accident leads to claims the life of whole family . All previous cases are probable a crime scene.By establishing methodical examination for the previous incidents , investigators should be systematic at crime scene while searching for physical evidence which can arrest the penetrators. Also, this process must be bone with care in order to preserve the decisive evidences from damages. At the scene the first officer arrived is responsible for defining the scene or evaluating the scene, establishing a systematic plan for collecting evidence without desiring them, secure the scene that is potential contain a critical evidence, recording the scene and determining the involved people in the case and packaging and submissions of evidence to forensic laboratories.In this report we are going to provide related information to crime scene investigation ::-Crime scene work-Types of physical evidence.-Chain of custody.-Recording crime scene.-Crime scene safety.Crime scene workCrime scene investigation is the meeting point of science , logic and law. It is a process that include purposeful documentation of the conditions of the crime scene. Also, it include the collection of any physical evidence that could explain what happened and who did it. If we take a look at who is presenting at crime scene?:1.Police officers: The first who arrive at a crime scene. They arrest the perpetrator if still around and call for an ambulance if necessary. They are responsible for securing the scene so no evidence is destroyed. 2.CSI unit:Who documents in a detail everything in the crime scene and collects any physical evidence. 3.Medical examiner:They present in case of homicide to determine a cause of death and not always present.4.Detectives:They interview witnesses and conduct with the CSI unit. They investigate the crime rely on witnesses and physical evidence. 5.5.crime scene technician:A highly trained professionals who analyses the evidence from a crime scene and present findings basing on the results of their analyses. The common works of the technician are: -Collect, process, and analyze fingerprints-Collect physical evidence such as weapons.-draw crime scene sketches.-determine which items should be collected at the crime scene-List the evidence and prepare it for safely transpotation to the crime lab-Take photos of the whole crime scene.6.Specialists :Including entomologists, forensic scientists and forensic psychologists to analysis the evidences.If we talked in detail about the duties of forensic scientist :Carrying out laboratory examination and analyses submitted by law enforcement.–Serving as expert witness in a court of law.-Carrying out tests using scientific techniques such as infrared spectroscopy spectroscopy mass spectrometry and scanning electron microscopy.-Ensuring all laboratory protocol and regulations are followed.-In putting data into computer programs and data base Information.-Preparing written reports .- -Coordinating activities related to crime scene collection preservation and transportation.-Serving as lesson between the forensic laboratory and crime scene Investigators.-Developing ,maintaining and updating work quality standards and operating procedures.-Coordinating work with other members of forensic term and without side.Forensic scientists usually perform their work in forensic or crime laboratory . They are responsible for comparing and interpreting the physical evidence that was brought by crime scene investigators. In specific circumstances, forensic scientists may present at the crime scene when the techniques of the collection or preservation of the physical evidence are in question.Types of crime scene:crime scene is the surrounding area where a crime has been committed. Such as forest, road, house or it could be any place. Crime provide clues that help in solving the crime which was committed. crime scene can either be primary or secondary. Primary scene is a scene where the actual crime took place. For example , in a murder Investigation , the primary scene would be the place where the murder occurred and the reason’s life was taken. In addition, there might be additional crime scenes involved as well and it would be the secondary crime scene. For instance , the criminal may have changed the place of the body after the murder. Let’s say the body was removed and placed in a forest then it would be the secondary crime scene. Secondary crime scene can help in finding more evidence which help in solving the case. Scientific method to a crime scene investigator: The successful certainly observations that the investigators found can be determine by the obtained results of the crime scene. The CSI should be methodical, reasonable and should understand:• What are the physical evidences at the crime scene?• The procedure to protect and collect these evidences. • The approach of how to obtain observations from these evidences.• linking all the obtained results.Type of evidences: • Class versus individual features : The investigator of the crime scene should have the ability to differentiate between the class features of physical evidences and the individual. It is not possible to identify all the physical evidences by only linking them to a related item or person. Therefore, the crime sense investigator (CSI) have the responsibility to discuss all the results of his forensic analysis with the scientist of the crime laboratory (lead detective) to find a cohesive and objective presentation of the evidence. Furthermore, biological or physical evidences can be included in the class or individual features and sometime exclude persons from the investigate procedure.• Class characteristics:It is not necessary that the physical evidence is related to a common origin with a high degree of certainty, hence, only a group of sources can only be located into a class and not a single. For the differentiation between the class evidences, it is not always possible for the investigator to find the exact or estimated probability values. A good example of class evidence is the polyester fibers. Investigation will collect information concerning the makeup polyester fiber, but it is not possible to state affirmatively that the fibers came from a specific rug. In addition, significance can be included to the place and amount of the fibers regarding the murdered, suspicious and/or crime scene. However, the investigators cannot accurately suggest that a specific rug was the source of the fibers. • Individual characteristics: Individual characteristics are generally considered as measurable differences evidences( physical and biological) which permits it to be related to a single source with a high level of accurately. This allows the investigators to identify the uniqueness of any single item of evidence. The mathematical likelihood which there are 2 matching sources of the distinct evidence of individual is beyond human understanding . The forensic examiner can illustrate in the court the scientific outcome which excludes the probability of two identical sources of evidences (biological or physiological) .• Direct evidences:Direct evidence means that no need of further investigation due to an established fact. A good example for the direct evidence is a recorded video of theft shop where the victim’s face is clear and easy to be identified or the permit of the eyewitness who was in the shop at the time of the shop robbery. Therefore, direct evidence does not need inference or hypothesis. It depends to the knowledge or perception of the investigator and then directly confirm or disconfirm the disputed fact. • Circumstantial evidence:Circumstantial evidences are the most evidences that are examined in the forensic laboratory, and it is depends to the forensic scientist to illustrate an inference of his analysis to provide the fact. Therefore, this type of evidence is relies on reasoning and not direct inference of a fact. To conclude, Circumstantial evidence is when the knowledge can be inferred from witness at trail. Chain of custody:At the crime place, all the information of the crime scene includes individuals, action, permit, and the investigation documents an important link in the chain of custody. Chain of custody is a formal paper in order to preserve the physical evidences. Starting with the arrival of the investigators and the emergency people at the location of the crime scene, different activities are scrutinized by hundreds of people with different roles in order to ensure that the justice is achieved. The protective procedures must be done immediately at the place of the crime scene in order to protect all the evidences. Then, the access to the crime scene should be controlled and the investigation procedure begun.The chain of the custody illustrates the transformation of the physical evidences from the place of the crime scene until the investigator releases the crime scene ……..of the disposal of the evidence. Searching for evidences:Crime scene technicians are in charge of providing a systematic strategy for Searching for physical evidences in order to preserve them from contamination and damages and to cover up all types of evidences. Therefore for each type of area there is a unique pattern should be followed to achieve the target. The patterns the used in crime scene investigations are:-Spiral search method: all most this method applies for large areas which contains tiny individuals in search. -Grind search method: it is also used for large areas that contains a abundant number of searchers. Also, it is often used in open and woodland areas.-Line search method: this pattern used in moderate area with a few number of searchers. -Quadrant search method: this method used for small areas. Figure 5: shows search patternsRecording crime scene:Recording is one of the critical and significant procedures in crime scene investigations for many reasons. It is important since it can help investigators to gain a comprehensive overview and inclusive knowledge about crime scene. For instance, it can provides a reliable material evidence according to their position and inter-relation to scene as well as, it can provides witnesses with ability to indicate the position of people and things within scene and time of crime . finally, it can support the court restricting the scene in details with potential evidence as well as refreshing memory of assessor of any incident. Recording crime scene can be done by photographs, notes and plans.Photography:Photography is one of the most significant methods that used for recording crime scene due to its ability to provides a virtual reality picture for an incident. Although, it can be useless or excluded by the court in case that is taken after any change made at the scene therefore, the most requirement for photography is the crime scene should be in unaltered condition. Photographs should include:-Primary crime scene and the adjacent area of area that incident occurs.-All objects at the scene which can be used in investigation.-All walls within the place that crime taken place and walls of adjacent place.-Weapons used , surface under corps and blood stains.-The relative position of objects as well as body with adjacent items in the scene. Notes: the purpose of writing notes is to provide an inclusive and certain records about observations , sequence of events and examination of crime scene. Notes which written at the time of incident may be it is not at logical sequence but that producible and can be fixed later on be reorganizing sequences in report. In addition, notes of events and observations maybe become non-significant or meaningful if it is written without indicating to some important details which is in relation with incident such as ( when, where, by whom , how…) therefore, notes should include:• Time and date that investigators arrived.• First person arrived at crime scene. • Officer who was in charge about this case.• Conditions of weather. • The is the incident and what was happening .• People and activities taken place.Investigators are in charge of Preserving evidence therefore, they shroud concern about their movement pathway while writing notes at crime scene in order to keep evidence without damages and contaminations.Plans:Plans are complement details of notes and photographs as well as it provides specific details about dimension and an overview for scene by showing scales and the exact position of items that related to the scene. There are several methods used to plans crime scene, Floor –plan is one way of planning both outdoor and indoor crime scene which illustrate the location looking down from above. For instance, cross-projection or exploded view is very close to floor-plans but it vary in walls that folded to uncover items that founded in the walls. Isometric projection sketches also used to indicate items of physical evidence like bloodstains. 3D or tree-dimensional sketches are new methods used in crime scene investigations which gives a virtual reality picture for the scene. However the most common plans used for crime scene investigation:1. Sketch plan ( rough sketch) :Sketch plan that drown at crime scene by investigators in order to show the position of items and their relations with another items. Sketch plan contains:-structure or appearance of items in sketches by indicating each item by a number or a letter and provides a ligand for items.-sketch should include time, date, and description of the crime.2. Scale plan (fished sketch):Scale plans sketches with accurate dimensional size, shape and position .it considers more accurate an sketch plan since it is concern about artistically view or appearance, accuracy and it is drown with scales. Collection of evidenceCrime scene investigation depend on the collection and the analysis of different type of evidence. There are physical and biological evidences. The physical evidence is any nonliving items and the biological evidence refer to any living being. Also, there is another important type of evidence called impression. Impression is a patterns of the items when it contact with soft surfaces like shoes patterns. The collection of impression which found in crime scene is very helpful and important to the investigation. According to Locard’s Exchange principle that perpetrator when enter a room he must leave something during contact with object or victim, and at the same time he must take something with him. There are many different types of evidence that can be collected from the crime scene such as :biological evidence including blood , hair ,body fluids and many other tissues.Blood should be collected in clean gauze pad or clean sterile cotton and allow to dry at room temperature. Also, it should be refrigerated and frozen and send to laboratory as soon as possible. If there is dried blood on clothing, first wrap the item in clean paper then place it in brown paper bag, seal and label the container and never try to remove the stains from the clothes. Hair can adhered to a piece of film and sealed with polythene bag. Figure 5:collect blood sample by clean sterile cotton. Latent print Including palm print, fingerprint and footprint.The collection of impression evidence need forensic specialist and can’t just packed directly because it can be easily destroyed.Fingerprint is the most important evidence which gives direct individual information because no one have the same fingerprint even the identical twins. Dusting fingerprints with special chemicals is a way to collect latent print. Figure 6:collection fingerprint by black powder. Trace evidence Including fibers, glass fragments and soil.Wrap the glass and fibers separately in clean paper( envelopes) with lapels and send it to the laboratory for test. Digital evidenceIncluding cell phone records , emails and internet logs. Electronic devises , charges , cables and manual should be collected. Also, cell phones, thumb drives and hard drives should be collected and examined by different tools and techniques in specialized lab.Drug evidenceDrug collection is based on the type of the drug. For instance, plant should not be packed in plastic because of the moisture and mold growth. And if the drug is in syringes or other sharp object it should be packed hard sided packaging like cardboard cartons or glass vials then labeled the biohazards. Figure 7: use glass tubes to collect drugs. Firearm evidence-Never send a loaded gun to the laboratory unless it’s taken in person. Also, firearm should never be shipped even if it is not cocked or on safety. -never shot from the gun before it is being examined in the lab. What is more, the firearm should not be cleaned the bore , cylinder or chamber before submitting – do not place pencil or any object in the end of the barrel when pick up a firearm.- record the caliber ,model ,make and serial number of the firearm.- firearm should be packed and place in strong wooden box or cardboard to make sure that the weapons will not shift during the transition.- gunshot and rifles should not be taken separately. Figure 8: gun collected in plastic bag. crime scene safety:This may refer to the procedures followed to control crimes there must be proper equipment to process the scene depending on the situation to protect the body. The scene has to be secured and protected before you process it ,this is for the safety of the crime scene officers and everyone else. The first one is to put on latex gloves which are important for protecting evidence because they keep you from leaving finger prints behind. They offer you protection from blood and other substances at the scene so remember to cover your shoes or boots with rubber boots when you are indoors. Photograph the shoes of everyone at the scene including the officers and the technicians, so that you can distinguish their imprints from those of suspects. Pay attention to the types of shoes or boots you wear they must have a good attraction and ankle support and will offer you protection from hazards such as nails. A helmet is also important they light and easy to store and eye protection there might be chemicals processed depending on the situation. Figure 9: wear latex gloves to protect you from dlood contaminations , diseases and protect you from bieng suspecious by lnot leaving your fingerprint. Personal protective equipment:Personal protective equipment (PPE) at the crime scene is very important for the crime scene investigator and they should take it into consideration in order to protect themselves from any hazards that may occur at the investigation place. PPE may include wearing gloves, shoe covers, full body suits and safety glasses. The first responders at the crime scene should immediately ensure that there is no threats to the investigators in the crime scene. Therefore, preventive measure must be followed in order to reduce the threat of any accidental contamination. ConclusionThis report gives important information about crime scene investigation. The persons who present in crime scene and their exact jobs. Moreover, the different types of crime scene (primary and secondary). Also, it shows information about the important procedures before starting the investigation such as approaching , medical assistant and crime scene securing. In addition, it gives all the important information about the whole investigation procedures and the crime scene safety.