What are two ways an autopsy helps establish the postmortem interval? What is one reason that supports the claim "It is often difficult to pinpoint the exact postmortem interval."?

Explanation:

1.The vitreous humor of the eyes helps determine the moment of death. To apply this technique, the researchers begin by analyzing the concentrations of potassium, urea, and hypoxanthine (a DNA metabolite) present in the vitreous humor of the corpse's eye, and enter the figures in a computer program. The software devised by the Galician scientists is capable of establishing with that information the instant in which death occurred.

Besides the traditional techniques for estimating the IPM are based on the study of parameters such as the rectal temperature of the corpse or one of its organs, such as the liver, on the examination of rigor mortis, or on cadaverous lividity. These methods are complemented by biochemical analysis of body fluids. One of them is the vitreous humor, the gelatinous fluid behind the lens of the eye.

2. Establishing the origin and cause of death after performing the autopsy is one of the forensic pathologist's major responsibilities. When these extremes are not clear or are debatable, it can become one of the most arduous tasks of the professional task. A technically perfect autopsy is a necessary, but not sufficient, condition to correctly determine the cause and origin of death.

The determination of the origin and the cause of death by the forensic doctor has legal, social, economic, health, etc. repercussions. Therefore, facilitating an incorrect cause of death can generate notable damages, ranging from inducing judicial errors (one of the worst offenses that can be committed in the medical-forensic exercise), to the pathologist himself being immersed in indefensible situations. It should be kept in mind that although autopsy reports are issued to the Court, in proceedings inaccessible to anyone who is not legitimized in the case, in practice they are public because copies are delivered to lawyers, family members, insurance companies, etc.

when comparing the cases, what similarities are there in the cases that suggest one person committed these murders?