Aco Martinović was born in 1979 in Montenegro. Publicly available information regarding his early life, education, and employment history remains limited. What is known is that he lived in or around Cetinje, a historic city in southern Montenegro, and was familiar with many of the individuals who later became victims of the 2025 shootings.

Martinović had a documented history of violent and criminal behavior prior to the attack. In 2005, he received a suspended sentence for violent conduct, indicating prior involvement in physical altercations. In later years, he was detained on multiple occasions for illegal possession of firearms and domestic violence, though these incidents did not result in long-term incarceration. Authorities did not publicly disclose whether he had undergone psychological evaluation as a result of these earlier incidents.

According to police and witness statements, Martinović had ongoing interpersonal conflicts within his community. On 1 January 2025, the day of the shootings, he was reported to have consumed alcohol throughout the day, a factor later cited by officials as relevant to his behavior, though no toxicology report had been released at the time of initial reporting.

Despite his criminal background, Martinović remained at liberty prior to the attack. The case would later spark national debate over firearms regulation, background checks, and the handling of individuals with histories of violence.

On the evening of 1 January 2025, at approximately 17:30 CET, a physical altercation broke out inside Kafić Velestovo, also known as the Velestovo Tavern, located in the village of Velestovo near Cetinje. Aco Martinović was involved in the brawl. Following the confrontation, he left the premises and returned to his residence, where he retrieved a firearm.

Martinović then returned to the tavern armed with a 9×19mm handgun and opened fire inside the establishment. In this first shooting, four men were killed, and four others were seriously wounded. Among those later confirmed dead were individuals personally known to Martinović, including the owner of the bar.

After the initial attack, Martinović fled the scene and traveled to multiple locations across the Cetinje area. At a second location, he killed four additional people. He then moved to two further sites, where he shot and killed two children and two adults. Among the child victims were two boys aged 8 and 13, identified as the children of the bar owner from the first attack location.

Some of the victims were killed in the nearby village of Bajice, while others were shot in and around Cetinje. Authorities later confirmed that many of the victims were either family members, acquaintances, or people personally known to the shooter, underscoring the localized and interpersonal nature of the violence.

Following reports of multiple shootings, Montenegrin police launched a large-scale manhunt. Roads leading out of Cetinje were blocked, and special police units were deployed. Residents were instructed to remain indoors as the suspect was believed to be moving between locations.

In the early hours of 2 January 2025, police located Martinović near his home in the Humci suburb of Cetinje. After being surrounded by officers, he shot himself in the head. He was transported to a hospital but died from his injuries shortly thereafter.

Police recovered the handgun used in the shootings, along with 37 spent shell casings and approximately 80 additional rounds of ammunition.

The shootings marked the deadliest mass shooting in Montenegro’s history and the second mass shooting in Cetinje within three years, following a deadly 2022 attack in the same city.

Montenegro’s President Jakov Milatović described the event as a national tragedy, while Prime Minister Milojko Spajić declared three days of national mourning and canceled New Year celebrations. The government announced plans to review and potentially tighten firearm regulations.

On 3 January 2025, Montenegro’s National Security Council announced new gun safety measures, including enhanced psychological and security checks for licensed gun owners, stricter penalties for illegal firearm possession, and a two‑month amnesty period for surrendering weapons.

Public protests followed in Podgorica, with demonstrators demanding the resignation of senior security officials. Additional demonstrations were held on 5 January 2025, reflecting widespread public anger and concern over public safety and gun control.