Sarajevo (AFP) – Bosnian police on Tuesday arrested the leader of a protest movement sparked by the unsolved death of a student that has brought together hundreds every night in the city of Banja Luka.

Davor Dragicevic, 49, whose son David died in March, “was arrested after having failed to respond to a police summons,” police spokeswoman Marija Markanovic told reporters.

For months, Dragicevic and his ex-wife have accused the authorities in Bosnian Serb-run entity Republika Srpska of “killing” their son, a charge officials have denied.

The body of the 21-year-old technology student was found in a stream in March.

Police called his death an accident, but his family suspected foul play, unleashing a wave of protests not seen in Bosnia since 2014.

A prosecutor later qualified the death as murder.

The group “Justice for David” who has been meeting every evening in Banja Luka’s central square for nine months now, last week gathered outside the parliament of Republika Srpska without approval by the authorities.

Some 20 protesters, including Dragicevic, were accused by a prosecutor of “threatening the security” of political officials.

Dragicevic was summoned for questioning but refused to report to the police station, the police spokeswoman said.

His ex-wife, David’s mother Suzana Radanovic, and several other group members were also arrested, including opposition party leader Branislav Borenovic and his party’s MP Drasko Stanivukovic. They were all accused of “violating public order,” police said.

According to local media, the demonstrators opposed police removing a “sanctuary” at what has become known as “David’s Square” where they have been gathering, bringing flowers and lighting candles every evening.

Protests “for David” have gradually turned into demonstrations against the rule of Milorad Dodik, a Bosnian Serb strongman whose party won an October election in Republika Srpska.

Since the end of the 1992-1995 war Bosnia has been composed of two entities — Serb-run Republika Srpska and the Muslim-Croat Federation — united by a loose central government.