Thursday, 19 September 2024
Thursday, 19 September 2024
At Tuesday’s Supreme Court hearing on the RG Kar Medical College rape and murder, Calcutta-based advocate Phiroze Edulji suggested three things he said could help crack the case.
Edulji had represented a petitioner in the RG Kar case before Calcutta high court last month, when the bench led by Calcutta High Court Chief Justice T.S. Sivagnanam ordered a court-monitored Central Bureau of Investigation (CBI) probe into the rape and murder of the postgraduate trainee doctor at RG Kar.
At the Supreme Court, Edulji – supported by solicitor-general Tushar Mehta, representing the CBI – raised doubts about the CCTV footage handed over to the CBI by the Kolkata Police.
While senior advocate Kapil Sibal, the Bengal government’s counsel, claimed that seven to eight hours of footage was handed over to the CBI in hard drives and pen drives, Edulji expressed doubt whether the “hash-value” of the device was protected by the cops.
Apart from the “hash value” reminder, Edulji suggested that the CBI should use genome sequencing and tower dumping technology to crack the rape-murder case.
Here’s what those terms mean:
What is the hash value – not hashtag – of CCTV footage?
Electronically stored information aka computer files contain a “hash-value”, which is the digital fingerprint of a particular file or device with numbers and letters assigned to the data contained by means of an algorithm.
Hash-values help in identifying duplicate files and track whether the files have been tampered with or altered in any manner. Digital forensic software are available to scan hash values of each document stored in the database and to flag duplicate ones.
During forensic tests, too, hash value of the files are checked. Even the slightest modification to a file will create a new hash value, which makes it different from the original file.
However, the investigators need to have access to the original file or document to compare whether the hash value is the same as that of the original.
After Edulji pointed it out, Chief Justice of India D.Y. Chandrachud on Tuesday instructed solicitor-general Mehta to confirm with the CBI whether the hash value of the files containing the footage from the cameras at RG Kar Medical College and Hospital submitted by the police are “protected”.
What is genome sequencing?
Genome sequencing is the process of determining the complete DNA sequence of an organism’s genome. Genome sequencing is believed to have revolutionised forensic science, aiding investigators in solving crimes and bringing justice to victims and their families.
The serial killer Joseph James DeAngelo Jr., a former cop and mechanic, infamous as the Night Stalker, the Original Night Stalker, the East Area Rapist and later on as the Golden State Killer, was apprehended in 2018 based on DNA evidence. Spread over two decades he was accused in over 13 murders, 51 rapes and a hundred-plus burglaries across California.
DeAngelo’s personal DNA profile was uploaded on a personal genomics website and a family tree created that dated back to the 1800s. Samples collected from DeAngelo’s car-door handle and garbage bin were referenced to those left behind by the Golden State Killer and were found to match.
Another American serial-killer, Dennis Lynn Rader, gave himself the nickname BTK Killer inspired by his modus operandi: Blind, Torture, Kill. He had killed at least 10 people in Kansas’s Wichita and Park City.
Thirteen years after the murders ceased, the investigators got a warrant to test a PAP-smear test taken from Rader’s daughter which was found to match with the DNA samples left in the fingernails of a victim.
Closer to home in 2018, an arrest made by police in Navi Mumbai had helped crack an eight-year old rape and murder of two children aged five and seven in Kurla, Mumbai. The investigators had collected the DNA samples from around 3,000 suspects. The DNA sample of the accused caught in another case in Navi Mumbai had matched with those found in the Kurla victims.
In the 1990s, the forensic experts had only four short tandem repeat (STR) markers, which have in three decades later transformed into multiple markers including autosomal STRS, Y-STRs, X-STR and Single Nucleotide Polymorphism (SNP).
With the use of multiple STR markers, investigators can process DNA which is highly degraded, minimal, contaminated or even decades old. The method helps generate DNA profiles with a higher resolution and improved sensitivity, assists in faster analysis and enhanced data interpretation.
How does genome testing help crack crime cases?
DNA profiling creates a unique genetic identifier of individuals and helps link suspects to crime scenes. The sequencing of DNA from unidentified remains can be matched with missing persons.
The DNA evidence available from cold cases can be processed through the advances made in technology. Relatives of suspects can be identified through a DNA database. DNA samples collected from one crime scene can be compared to those from others thus helping in making connections between multiple crimes. The DNA evidence can also help rule out other suspects in a particular crime.
What is tower dump technology?
This is a data extraction procedure used to collect information from a specific cell tower, capturing details of all mobile devices that are connected to the tower during any specific duration of the day.
Law enforcement agencies use the technology to track suspects in a criminal investigation, their specific location at the time when the crime was committed.
The tower dump helps the sleuths to find out the exact date and time when a mobile phone was connected to a specific tower, identifies the particular device, including its model and type, the number associated with it, information on the user, whether the interaction between the caller and the person at the other end was via a call or SMS, also whether the call was received by the particular device being tracked or it was used to make the call and the duration of the call, whether the device was stationary or on the move.
The information collected from the tower dump helps the investigators to analyse the call patterns of the suspects and also establishes his or her call history, helps track online activities and can help place the suspect using his device to whether the person was in the vicinity of a scene of crime.
This information is given to police by mobile service providers.
