**4.2. Analysis of the Y‐chromosome**

**•** Skeletal muscles or heart muscle;

Apart from whole blood, epithelial cells from oral mucosa as well as hair are considered to be important sources for DNA analysis, being frequently used. In the case of epithelial cells, they are harvested with a sterile bud or brush. After harvesting, they are wrapped in a paper envelope and put to dry. Hair is taken by pulling, 5–10 with the root being enough for the

The hair is wrapped in paper envelopes or plastic wrapping and is kept in a dry environment,

In comparison with the biological samples mentioned earlier, in the case of tissue, muscles, organs, or skin, the harvested volume needs to be between 2 and 4 cm. Right after harvesting, the DNA extraction and isolation follows because both its quantity and quality decrease in

In forensic DNA typing, short tandem repeats (STR) or microsatellites are the most frequently genotyped in order to distinguish between individuals, to tie an individual to a crime or to exonerate the innocent. STRs were discovered in the 1980s [9] and since then, they are the "gold standard" in human identification in forensic investigations. They consist of mono‐, di‐, tri‐, tetra‐, penta‐, and hexa‐nucleotide repeat. An individual can be either homozygous (with the same number of repeats) or heterozygous (different number of repeats) in a certainly locus.

STR profiles obtained from biological samples found at crime scenes are compared with other profiles of known suspects and are identified by police or are included in a national forensic DNA database [11]. Also, the STR profiling is used in paternity/maternity testing, disaster

Tetra‐nucleotide repeats are used for genotyping in forensic DNA analysis [10].

DNA analysis is a complex process which consists in the following phases:

**4. Methods used in forensic for human identification**

**•** Peripheral vessels;

90 Forensic Analysis - From Death to Justice

**•** Other tissue types.

at room temperature [8].

**a.** DNA extraction;

**b.** DNA quantification; **c.** DNA amplification;

**4.1. Autosomal STR profiling**

time and depend on the storage conditions.

**3.3. Characterization of the DNA analysis**

**d.** Detection of the DNA amplified products.

**•** Long bones;

analysis.

In forensic medicine, the Y‐chromosome has only one useful property: It is present only in males. Thus, in crime cases, the investigators expect to find Y‐chromosome at the scene. Also, when talking about male–female ratio in body fluid mixtures, such as rapes, by analyzing the Y‐STR component, the investigators can obtain more information regarding the male compo‐ nent. It is well known that vasectomized or azoospermic rapists do not leave sperm traces, and it is impossible to find spermatozoa on the microscopic examination. In such cases, the Y‐STR profiling is very useful, offering information regarding the identity of the rapist [17].
