Yes, from 1901 it is possible to identify people from fingerprint recognition, from their ear print, from their teeth or bite impression, from their skin residues (sometimes under the jewelry, especially rings), from their retinal vessels and also from their blood typing (A, 0, AB, B), which were discovered by Karl Landsteiner in 1901. There are only four different types and lots of people can share the same type. This kind of marker could be used only to exclude somebody from a crime

Fingerprints have been used since 1901, while DNA fingerprinting was used for the first time for a maternity test, liked to an immigrate dispute. This immagration case opened door for using DNA fingerprinting in forensic cases and for identity determination. Moreover, by that time, it began to be used to aid a criminal investigations. 

There are many potential source of DNA for forensic analysis and the most common are: BLOOD, that is an excellent source of human DNA in white blood cells; SEMEN, which contains sperm cells; SALIVA, which contains cellular material; the HAIR FOLLICLE at the base of human hairs contains cellular material rich in DNA; SKIN and DANDRUFF; SWEAT STAINS, which contain skin cells sloughed off; VAGINAL FLUIDS, NASAL SECRETIONS and URINE, which contain mucosal surfaces, which do contain DNA; FECES, which contain digestive system cells rich of DNA.

Restriction fragment length polymorphism (RFLP) is a technique invented in 1984 by the english scientist Alec Jeffreys during research into hereditary diseases. It is used for the analysis of unique patterns in DNA fragments in order to genetically differentiate between organism. 
The RFLP technique exploits these differences in DNA sequences to recognize and study intraspecies variation.

A restriction enzyme is an enzyme that cuts DNA at or near specific recognition base sequences known as restriction side. These enzymes are found in bacteria. 

Restriction enzyme are used for biotechnology research, especially for DNA cloning and DNA fingerprinting. Different restriction enzymes recognise and cut different DNA sequences. Restriction enzyme are used to digest genomic DNA for gene analysis. This function allows to detemine how many copies of a gene are present in the genoma of  person, or how many mutations have occurred in a population.

2. Before casting the gel, the tray and comb should wipe with ethanol.

3. Make sure that the gel in the Chamber is immersed in the TAE Buffer.

4. Labelings should be  proper.

5. Ensure that the connections should be proper.

6. Before the  incubation step, ensure that the water bath is set at the correct temperature that we required or not.
Which piece of information can be find out from a DNA pattern bands?

If you get, through electrophoresis, the same DNA sample found at the crime scene, the person from whom that DNA fragment pattern was taken is probably the culprit of the murder.

The pairing of nucleotides within the DNA double-helix is complementary which consist of Adenine (A) pairing with either Thymine (T) in DNA or Uracil (U) in RNA, while Cytosine (C) pairs with Guanine (G). So if a sequence is palindromic, the nucleotide sequence of one strand would be the same as its reverse complementary strand. An example of a palindromic sequence is 5’-GGATCC-3’, which has a complementary strand, 3’-CCTAGG-5’.