The Punjab government may rely on a plethora of evidence for its prosecution against the suspect in Zainab Amin’s rape and murder case, but they should be wary of the fact that they cannot rely solely on DNA evidence, let alone any single form of evidence, for conviction.

In fact, corroboration of different kinds of evidence — medical, physical and ocular — will be needed to convict the suspect, and the state’s competence will be tested on a heightened level.

The Punjab government missed a key opportunity to enact tailor-made legislation for rape cases when, in a public interest jurisdiction matter (Salman Akram Raja & another v. Government of Punjab, 2013 SCMR 203), a series of suggestions and guidelines were proposed to Punjab by the supreme court on how the police, hospitals and doctors should handle cases of rape.

While the suggestions primarily related to protecting the victim from the accused during all stages of investigation and trial, it included guidelines which could have safeguarded the government’s interests as well.

Also read: Zainab's murder: the state must not succumb to mob mentality

This included the mandatory administration of DNA tests and preservation of DNA evidence in rape cases, along with separate screens for vulnerable witnesses so that they do not have to face the accused persons during trial.

The then prosecutor-general of Punjab had said that legislation was likely to be made in this regard. Regrettably, no such legislation has been enacted in the province yet. Therefore, the Punjab government will have to rely on existing laws to convict the suspect in Zainab’s case.

Since there is no direct evidence in this case due to the victim being deceased and there being no known, direct witnesses to the crimes, the prosecution will have to rely on a string of other forms of evidence to connect the suspect with the offence without any reasonable doubt.

Proper post-mortem examination, correct semen grouping and matching of the swabs, untainted recovery of physical evidence from the scene of the crime, consistent eyewitnesses’ testimony, and finally, accurate forensic analysis, will all play a part in the prosecution’s case against the suspect.

Persons directly involved with the investigation of the case will serve as crucial evidence against the suspect. The Medico Legal Officer (MLO) who conducted Zainab’s post-mortem examination will be called upon to verify the contents of the examination report, along with the chain of events leading to the issuance of the report.

Similarly, the police team (e.g., the investigating officer) that seized the physical evidence in the commission of the crime (e.g., the suspect’s jacket) will be called upon as witnesses.

The MLO and the investigative team will be subject to extensive cross-examination on when, where and how they obtained and preserved their evidence and/or findings.

Any substantial disparity discovered in or between the investigation and the post-mortem report, including any major contradictions in the recollection of the events or any improper collection/preservation of the evidence, will severely taint the prosecution’s case.

While there might not be direct witnesses to the commission of the crimes against Zainab, witnesses of interest, including those who may have seen or observed the suspect before or after the crimes, will be called upon to narrate relevant facts as circumstantial evidence.

Different witnesses’ narrations will be compared and contrasted to determine the sequence of events leading up to the commission of the crime and after.

The consistency amongst the witnesses’ testimonies and any presence or absence of preconceived animosity/ill-will against the accused will play an integral role in determining the veracity of their statements.

The prosecution, and consequently the state, will have to be especially wary of out-of-court intimidation tactics by the suspect or other vested parties.

Such tactics have notoriously adversely impacted trials of rape, whereby eyewitnesses often change or resile from their statements due to intimidation tactics employed against them.

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Overwhelming and irrefutable evidence of the above (i.e., medical, physical and ocular evidence) may be strong enough to convict the suspect.

However, any significant discrepancy in the above will force the prosecution to rely on forensic evidence, including DNA, as additional corroborative evidence.

The aforementioned 2013 supreme court judgment held that DNA evidence, while not conclusive on its own, could be considered as valid evidence in corroboration with other pieces of evidence.

In 2015, however, the supreme court, in the context of a biochemist’s DNA report in a kidnapping and murder case, held that DNA evidence was not admissible due to the fact that there was no sanction of law regarding the admission of such.

While this may have created some ambiguity on the relevance of DNA evidence in rape cases, the federal legislature in 2016 passed the Criminal Law (Amendment) (Offences Relating to Rape) Act, 2016, which amended Section 164 of the Code of Criminal Procedure by adding that samples of DNA, where practicable, shall be collected and sent for examination at the earliest.

Therefore, the Punjab government may introduce DNA evidence in Zainab’s case. However, the mere availability of such evidence will not tantamount to admission or acceptance of it, as the forensic/DNA expert will also be subject to cross-examination and scrutiny.

While DNA evidence can serve as a powerful evidentiary device, it can become contaminated or corrupted by errors in laboratories from factors such as coincidental matches, time, temperature, contact with other contaminants, and exposure to other elements.

The forensic expert will have to back the collection, preservation and findings meticulously before the court of law.

Related: Pakistan's flawed forensic investigation in rape cases is the weak link in the justice system

Finally, the accused may at some point argue that he made an extra-judicial confession, which is a confession made out of court, and not as a part of a judicial examination or investigation.

Such a confession would need to be corroborated by other evidence by the prosecution, or else it would be insufficient to warrant a conviction, especially if the confession was made before a person of influence and authority.

Such evidence can at best be corroborating evidence, and is held to be the weakest type of evidence and no conviction on can be made on such evidence by itself.

The prosecution's case hinges on narrating an unbroken chain of corroborative pieces and links of evidence against the suspect. If the circumstantial evidence connects the accused with the offence without any reasonable doubt, it will form the basis for the accused’s capital punishment.

This article was originally published on January 29, 2018.