A woman has been arrested for killing her ex-boyfriend with a brick after he bottled her new boyfriend at their son’s birthday party.

Gabriela Macarena Nunez, 27, and Gonzalo Martinez, 25, separated in 2020 after a five-year-long relationship that left them with two children aged two and three.

Martinez had been served with a restraining order, but the couple agreed to spend the day together to celebrate one of their son’s birthdays on Saturday, 2nd October.

Local news site TN reports that the celebrations were held at Nunez’ home in the department of Pocito in the Argentine province of San Juan.

Nunez’ new boyfriend, Marcelo Oscar Roca Castro, 21, was present at the party, which reportedly angered Martinez, who was unhappy his ex was in a new relationship.

An argument broke out, which culminated in Martinez allegedly striking Roca Castro with a beer bottle.

Martinez was about to get in a taxi to leave with his two children without their mother’s permission when Nunez allegedly picked up a brick and threw it at her ex.

According to reports, the brick allegedly hit him in the neck, causing a brain haemorrhage that killed him instantly.

The whole incident was allegedly witnessed by the taxi driver, who the police now consider the key witness in the investigation.

An ambulance had already taken Roca Castro to hospital, where he had his wound stitched up. It was only when he was receiving treatment that he found out the alleged murder had taken place. He was later discharged.

The police arrived at the house shortly after the incident and arrested Nunez on suspicion of killing her ex.

The news site Infobae reported that she underwent a psychiatric examination, but the results were not reported.

The couple’s two children along with Nunez’ two other children, who are not related to Martinez, have been taken into temporary state care, but they are expected to be taken in by other members of the family.

The investigation is ongoing.