In a pivotal moment during the trial of Jozef Puska, who stands accused of the murder of schoolteacher Ashling Murphy, a forensic expert’s testimony revealed that male DNA profiles found under the victim’s fingernails matched those of the defendant. Dr. Lorna Flanagan of the Forensic Science Laboratory testified that the likelihood of the DNA profile belonging to someone other than Puska was just one in 14,000.
Dr. Flanagan explained that she had conducted male-specific DNA profiling, known as Y-STR profiling, on the samples collected from beneath Ms. Murphy’s fingernails. This advanced technique zeroes in on the characteristics of the male Y chromosome, allowing scientists to exclude female DNA from the analysis. She likened it to a magnet that selectively extracts male DNA from the “haystack” of female DNA.
Although the samples taken from both the left and right fingernails of Ms. Murphy were expected to contain primarily female DNA, Dr. Flanagan successfully developed Y-STR profiles from the scrapings and compared them with profiles derived from blood samples obtained from Puska at St James’ Hospital and a sample provided by him while in custody. The male-specific profiles from the victim’s nails were conclusively matched with those of Puska.
Dr. Flanagan emphasized that the statistical probability associated with Y-STR profiles is lower than that of full profiles due to the unique combination of elements in each complete DNA profile. During cross-examination, she noted that Forensic Science Ireland’s Y-STR database contains approximately 28,000 samples, representing various European ethnicities, including ethnic Romany Slovaks.
Detective Sergeant David Scahill provided further testimony, indicating that he had tracked the movements of Puska’s two brothers on the day of the murder. This investigation was conducted in light of the DNA evidence presented. CCTV footage confirmed that neither of the brothers was near the location where Ms. Murphy’s body was discovered after 2 pm on January 12, 2022.
Additionally, Detective Superintendent Patrick O’Callaghan informed the court that another individual, initially arrested in connection with the murder, had been released from custody. This decision was made after the individual provided consistent accounts of his movements, which were corroborated by his mother and grandmother. Notably, this individual’s DNA did not match the samples collected from the crime scene or from Ms. Murphy.
The trial continues as new evidence and testimony shed light on the tragic murder of Ashling Murphy, and the courtroom remains captivated by developments in this high-profile case.
