Law-enforcement officials have questioned Suren Khachatrian, the controversial governor of Armenia’s Syunik province, in connection with a violent attack that was allegedly led by one of his sons, it emerged on Tuesday.

The May 2 incident in the regional town of Goris reinforced a widely held belief that Khachatrian and his equally violent relatives enjoy impunity thanks to their loyalty to President Serzh Sarkisian.

It left two Goris residents severely injured. The 32-year-old Harut Zakarian lost vision in one eye while his elder brother Mushegh suffered a broken nose after they were attacked by a large group of other men. They claim that they attackers were led by Khachatrian’s notorious son Tigran.

Armenia’s Investigative Committee, a law-enforcement agency investigating the assault, reluctantly interrogated the 21-year-old on May 16 amid a media and opposition uproar in Yerevan. But he was not detained or charged as a result. Nor have the investigators levelled accusations against anyone else so far.

According to an assistant to a lawyer for Suren Khachatrian, the Syunik governor insisted during the questioning that his son is innocent. “Tigran Khachatrian had no part in the incident. “He only separated people,” the assistant told RFE/RL’s Armenian service (Azatutyun.am). He refused to give other details.

Khachatrian claimed in the immediate aftermath of the incident that Tigran was not in Goris on May 2.

Meanwhile, the injured brothers’ mother, Anahit Galstian, decried what she sees as a lack of progress in the probe and warned the Investigative Committee against a cover-up. “We won’t keep silent,” she said, insisting that her sons were beaten up by Tigran Khachatrian and dozens of his “thugs.”

Galstian also reiterated that they received threats from the governor’s son over the phone shortly before the incident. She challenged the investigators to listen to the audio recordings of their phone calls.

The beating occurred almost two years after Tigran and his father’s bodyguards clashed with a Goris businessman, Avetik Budaghian, and his brother Artak outside the Khachatrians’ local villa. Avetik was shot dead while Artak was seriously wounded in the incident.

Tigran and one of the bodyguards were arrested in the following days only to be cleared of murder charges and set free two months later. Law-enforcement authorities said the gunshots fired by them constituted legitimate self-defense.

Despite denying any involvement, Suren Khachatrian was sacked in the wake of the 2013 shootings. But he was reinstated as Syunik governor a year later.