With an increase in criminal activities, a large number of crime cases are reported every day. These violent crimes are usually suicidal, homicidal, or accidental in nature. In forensics investigations, blood is the most significant and valuable biological evidence, which is found very frequently at crime scene. The main motive of the collection of biological samples from the crime scenes is to get the genetic information from collected samples and use that information for the identification of the suspect. A DNA profile indicates the person's identity and the pattern of the streaks reveals the crime scene position, which means both DNA profiling, and bloodstain patterns serve as a significant tool for the identification of the perpetrator. The blood found at the crime scene in the form either blood pool or stain, needs to be collected, preserved, and analyzed by the examiner on the spot or in the laboratory. The dried bloodstains can give an indication of the relative age of a trauma and timing of its occurrence , which can be extremely helpful to investigators in determining whether the stain was related to that crime scene or not. Numerous researchers gave their contribution in the development of a plethora of methods for the determinations of age of dried bloodstains. In the present study, an attempt has been made to review all those conventional and modern techniques used by various scientists to estimate the age of the bloodstains. Keywords:- Criminal, Suicide, Homicide, Biological Evidences.