In a Los Angeles courtroom, the preliminary hearing of indie-pop singer D4vd—charged with the murder, sexual abuse and dismemberment of 14-year-old Celeste Rivas Hernandez—has turned on a dispute over forensic testing. Defense attorney Blair Berk pressed criminalists on why chain saws found in the defendant’s garage were not swabbed for touch DNA, given that multiple people lived at the residence. According to testimony, initial chemical tests showed no blood on the blades, and prosecutors argued that a suspect’s DNA would be ubiquitous in his own home. Meanwhile, prosecutors presented digital tracking data they say places the singer at the Hollywood home on the night of the killing and later at remote sites in Santa Barbara County where the victim’s passport was recovered. The judge must now determine whether probable cause exists to proceed to trial.

Viewed from the United States, the D4vd proceedings illustrate a broader trend in which defence teams increasingly probe the limits of forensic analysis. In another case, lawyers for Florida defendant Steven Gress, who has admitted to torturing and dismembering a teenager and requested execution, successfully insisted on a competency review before he could waive trial. And in Texas, an arrest last month in a 14-year-old cold-case murder relied on investigative genetic genealogy (IGG), a technique that US law enforcement agencies describe as a transformative tool. Police said DNA lifted from a plastic fork taken from the suspect’s trash matched blood found at the 2012 crime scene, leading to the charging of a former friend of the victim. The FBI’s Dallas field office has praised IGG as one of the most valuable instruments available to investigators, with Arlington police reporting roughly 14 unsolved cases resolved through new DNA technologies in the past 18 months.

In Italy, a separate case in the Sardinian village of Bari Sardo underscores how witness statements and allegations of stalking can shape fast-moving investigations. A 16-year-old surrendered to carabinieri after a 19-year-old man who had allegedly been harassing his sister was fatally stabbed. Investigators are examining claims that the deceased had persisted in unwanted advances toward the victim’s sister and had grown more aggressive in recent weeks, reportedly including a public insult. Following an earlier attempted vehicle-ramming, a confrontation escalated, and the minor now faces a homicide charge in a juvenile penal institute.

Legal analysts in London note that, across jurisdictions, the intersection of rapidly evolving DNA technologies with established criminal procedure is generating procedural flashpoints. The US cases highlight how courts must balance the probative value of genetic evidence against ever-more sophisticated challenges to chain-of-custody, testing protocols, and interpretive assumptions. In the Italian system, the emphasis often falls more immediately on witness credibility and the dynamics of interpersonal conflict. The D4vd hearing is expected to conclude within days, while the Gress competency review in Florida and the Texas suspect’s first court appearances will set the stage for jury trials that may pivot on forensic arguments.