DNA And Related Case Study


Deoxyribonucleic acid (abbreviated DNA) is the molecule that carries genetic information for the development and functioning of an organism.

Every person has a different genetic code which gives information about that person. Forty-six (46) chromosomes contain this code and made of a chemical called DNA that is the short form of deoxyribose nucleic acid. DNA is powerful investigative tool because, with the exception of identical twins, no people have the same DNA. Therefore, DNA evidence can be collected from a crime scene, can be linked to a suspect or can eliminate a suspect from suspicion.

Also Read: How to Extract DNA?

Sources of DNA Samples

These are the sources from which the DNA samples are collected by forensic experts:

  • Blood
  • Saliva
  • Semen
  • Urine
  • Feces
  • Hair with tissue
  • Nail with tissue
  • Teeth
  • Bone
  • Tissue
  • Cells
Picture Courtesy: Verywell / Jessica Olah

Some Cases Solved by PFSA On the Basis Of DNA

Here are some cases that are solved on the basis of DNA analysis by Punjab Forensic Science Agency (Pakistan).

1. Death penalty imposed on man for raping his nieces: Case adjudicated on the basis of PFSA Reports

Two minor girls, aged 8 and 12, reported to their mother, a famous Pashto singer, that their maternal uncle had repeatedly sexually assaulted them. The perpetrator, who lived in the same house, would also intimidate the girls by showing them videos of the killing of children on their mobile phones so that they would not report the molestation out of fear. Due to professional commitments, both the singer and her husband were away from home most of the time, which is why she called her brother from Swat to take care of the girls and ensure the safety of the home.

The mother of the minor girls initially did not believe the story, but one morning she woke up to her younger daughter crying. She rushed to her daughter’s room and found her brother raping her daughter in the nude. She burst into tears, but her brother managed to flee the scene. He was subsequently taken into police custody and taken to the PFSA for DNA analysis.

Both girls were taken to the emergency room for a medical examination. Examination of both girls revealed a ruptured hymen along with inflammation of the perineal area. The girls’ vaginal swabs and clothing were submitted to the PFSA for DNA analysis. Seminal material was identified on the pants of one minor girl. Seed was also found on a towel and a pair of woolen gloves used for wiping. A male DNA profile obtained from sperm from these items matched the suspect’s DNA. So the case was solved based on the DNA profiling results.

Following his arrest, a case under Section 376 (rape) and Section 506 (criminal intimidation) of the Pakistan Penal Code (PPC) was registered against the assailant at the Rawat Police Station in Rawalpindi. The crime was proved in the trial court and the Rawalpindi Additional District and Sessions Judge sentenced the convict to death and also fined him Rs 0.6 million.

Also Read: DNA Fingerprinting

2. Child Rapist caught with the help of PFSA DNA database

In 2017, a case of rape of a 9-year-old minor girl was reported in a small district of Punjab. The medical examiner noted several physical injuries on the minor’s private parts, which indicated brutal sexual violence. The assailant was not known to the minor girl or to the witnesses of the incident, but the police arrested the suspect, who accepted the crime and was later brought to the PFSA for DNA analysis. A careful analysis of the evidence collected from the body and clothing of the victim of this unfortunate incident was carried out at the PFSA.

Seminal material was identified on the evidence items tested, but the suspect was ruled out as the source of the foreign male DNA that was recovered from the evidence. Thus, the acquittal of an innocent man could be hinted at based on DNA analysis. The unknown DNA profile was uploaded to the PFSA DNA database and maintained on file.

In April 2018, a suspect was caught in Karachi who, during interrogation, confessed to committing a rape in Punjab. The Sindh Police requested the PFSA to create a DNA profile of this suspect for a database search, and the Directorate General of the PFSA also agreed to do so. A DNA profile was developed from samples submitted by the Sindh Police. When the PFSA DNA database was searched, the DNA profile of the Karachi suspect matched the foreign DNA obtained from the swabs of the minor girl, thus solving this heinous crime. A DNA database is used to store DNA profiles of people, which allows searching and comparing DNA samples taken from the scene of the crime with the stored profiles.

The most important function of a forensic database is to make matches between suspects and crime scene samples. This practice provides evidence to support criminal prosecutions and also leads to the identification of potential suspects in criminal investigations. The DNA and Serology Department at PFSA is a state-of-the- art forensic facility that assists law enforcement/investigative agencies and  courts in administering justice to the people. The DNA database at PFSA is a unique facility in the country. It took years of effort to develop the rich DNA database at PFSA, but that effort is now bearing fruit!

3. Zainab Rape Case

Two-and-a-half-year-old Zainab, abducted from Charsaddy, was raped and killed before her body was dumped in Peshawar’s Daudzai area, police said. Hospital sources said a medical examination revealed that the minor was raped 18 hours ago, after which her body was hacked with a knife.

The girl’s clothes were found where her body was found. Officials said the victim’s DNA samples have been sent to Khyber Medical College in Peshawar, while the National Database and Registration Authority (NADRA) has sought the help of other agencies to trace the culprits. The girl’s father registered a complaint at the local police station after Zainab went missing on October 6. In his police complaint, he said the girl went out to play around 1 pm and did not return home. He added that the family searched all possible places but could not find her.

Charsadda District Police Officer (DPO) Mohammad Shoaib Khan said the police had initially registered a First Information Report (FIR) at the Prang Police Station against unknown kidnappers. However, after the body was found, it was turned into a murder case. According to the police, eight suspects were arrested. Sanaullah Abbasi, Inspector General of Police Khyber Pakhtunkhwa, confirmed in a statement that the suspects in the case had been arrested but did not give any details, saying it would “affect the investigation”.

Zainab’s father said the family had no enmity with anyone. He demanded that the government catch the culprit so that he can ask him what his daughter did to him to commit such a crime. “Today it is my Zainab, tomorrow another Zainab may suffer,” he lamented.

Khyber Pakhtunkhwa Chief Minister Mehmood Khan ordered the immediate arrest of those involved in the incident. He said the incident was very heartbreaking and inhumane and those involved in the heinous crime would be made an example. Meanwhile, the hashtags #JusticeforZainab and #AnotherZainab were used on Twitter on Thursday to express outrage over cases of child abuse and murder. Photos of the two-and-a-half-year-old’s body also circulated on social media with many users comparing the incident to the rape and murder of 8-year-old Zainab Amin in Kasur in 2018. Zainab Amin, who went missing on January 4, was found dead five days later. As the 12th such incident to occur within a 10-kilometer radius of Kasur in one year, Zainab’s rape and murder sparked outrage and protests across the country.

The suspect’s polygraph and DNA tests were confirmed to match samples from at least eight underage girls, including Ansari, who were raped and murdered in the same neighborhood. Ali was a 24-year-old mechanic who lived in Ansari’s neighborhood, and further investigation revealed that he even participated in the protests after Ansari’s body was found. On 17 February 2018, an anti-terrorism court at the Lahore Central Jail found Ali guilty of raping and murdering Ansari and twelve other minor girls.

The court awarded him four counts of death, one life sentence, seven years imprisonment and a fine of ₨3,200,000. He was executed by hanging on 17 October 2018 at 05:30 local time. More than two years after the Zainab case, the National Assembly passed the Zainab Warning, Response and Recovery Act of 2019, which seeks to speed up the investigation and punishment of child abuse perpetrators.

About The Author

This article is written by Muhammad Arjamand, currently pursuing BS Forensic Science from University KFUEIT RYK, Pakistan.

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