A cold, murderous instinct marked the spate of killings by Rajendran D, the 41-year-old MBA holder from Tamil Nadu, who was sentenced to death for the homicide of Thiruvananthapuram native Vineetha. It was, however, his impulsive reaction that left behind a vital clue to prove his presence in the scene of crime.

Scientific officers from the Forensic Science Lab scraped blood stains off the wall of the ornamental plant shop where Vineetha was murdered and then separated two DNA profiles: one of Vineetha and another of Rajendran. It matched with other blood samples, including the one recovered from the knife used to kill Vineetha. What could have been assumed and treated as the victim's blood stain was painstakingly separated to build separate profiles and strong evidence.

Sunitha Krishnan, the Scientific Officer with the Forensic Science Lab, spent four hours at the crime scene and collected 10 material objects like blood stains from flower pots, flex sheet, sand strainer and outside wall. The one collected from the wall of the scene of crime through careful scrapping was crucial. Material blood stain trace evidence was found in three items collected from the scene. Forensic examination confirmed the physical proximity of the accused and victim at the same location on the crime scene.

Vineetha had put up a last, desperate defence while Rajendran outpowered her from behind and started cutting her throat and stabbing her neck repeatedly. She placed her hand between the knife and the neck, and in the process, Rajendran cut himself, sustaining wounds to three fingers in his right arm. His first reaction was to shake his wounded arm, leaving a spatter of blood on the wall. Blood-stained evidence collected by the Scientific Officer Sunitha Krishnan from the wall in the scene of crime close to the place where Vineetha's body was found was a crucial material circumstance to prove Rajendran's presence on the scene of crime.

"It was the turning point, establishing the element of criminality and linking his presence with the place of occurrence. The place where he was caught on CCTV was just 20 metres from the crime scene, but there needed a strong link to prove his presence. Blood stains from wall-scrapings contained a mix of Rajendran's and Vineetha's blood. DNA analysis separated the profiles," said Special Public Prosecutor P P Salahudeen.

DNA and serological analysis of the blood stains showed that the accused and the victim were available on the scene of crime at similar time. The prosecution proved that Rajendran either shook his hands or touched the wall to produce a spatter of blood stains on the wall. This was an instinctive reaction after he sustained injuries to his fingers. Since Vineetha's neck was stabbed using a sharp-edged knife, the vertebrae and blood vessels were cut, which produced spattering of blood at immense force as severance of blood vessels caused blood to spurt out and spread in nearby places, according to the prosecution findings mentioned in the court order.

Already an accused in three murders in Tamil Nadu, Rajendran had done everything to clean up the trail. CCTV footage showed him walking with his right arm in his pocket after the crime. He even deliberately placed his right palm on an electric coconut scraper of a tea stall to change the nature and characteristic features of the wound. But before all those acts, he had left behind a stain in a crime that proved crucial in establishing his guilt.

G Sparjan Kumar, who was then the Thiruvananthapuram City Police Commissioner, who led the probe, said that his reaction upon sustaining an injury led to a key finding. "Every criminal leaves behind something for the cops. In this case, it was his blood mixed with that of Vineetha, which was picked up from the wall," he said.

Vineetha, 38, was murdered by Rajendran in February 2022 at a plant shop in Thiruvananthapuram to rob her of a gold chain weighing 4.5 sovereigns.