YEREVAN—The heads of Armenia’s National Security Service and Special Investigative Service both said that the role of former prime minister Hovik Abrahamyan in the March 1, 2008 post-presidential election crackdown on protesters is a “theory that needs to be verified.”

NSS Chief Artur Vanetsyan and SIS chief Sasun Khachatryan both agree that Abrahamyan’s role in the March 1, 2008 events should be probed. The NSS on Wednesday arrested Abrahamyan’s brother, Henrik, after raiding an abandoned industrial plant in the village of Mkrtchyan where they found a large cache of weapons, including Kalashnikov assault rifles, machine guns and other fire arms.

Along with Henrik Abrahamyan, the NSS also arrested Ambik Gevorkyan, the registered owner of the property, which the NSS deems is effectively owned by the former prime minister.

The NSS and the SIS are working together to establish the origins of the weapons and determine whether any of them were used during the March 1, 2008 crackdown during which eight civilians and two police officers were killed in clashes between protesters and the police.

The prosecutor general has already filed charges of breaching Armenia’s constitutional order against then president Robert Kocharian, defense minister Mikael Harutiunyan and the chief of staff of the armed forces Yuri Khachaturov. Kocharian and Harutiunyan were remanded into pre-trial custody, while Khachaturov was released on bail and allowed to return to Moscow where he serves as the Secretary General of the Collective Security Treaty Organization.

The charges stem from claims by prosecutors that the high-ranking leaders at the time of the crackdown engaged the army in the election process—a violation of the current and previous constitutions of Armenia.

Hovik Abrahamyan was Armenia’s prime minister until September 2016 when he stepped down over reported disagreements with then president Serzh Sarkisian. Abrahamyan resigned from Sarkisian’s ruling Republican Party of Armenia in early 2017.