The son of a murdered Sinn Féin activist has become the first person in almost 30 years to be charged in connection with a paramilitary display at a republican funeral.

Conor Casey (38) placed a tricolour on the coffin of his best friend, dissident republican John Brady, before three masked men fired shots over the coffin in Strabane, Co Tyrone, last October.

Casey's sister, Fiona Connolly, said: "My brother had nothing to do with the firing party. He wasn't one of the masked men. He was at the funeral in a white shirt and black tie. He had nothing to hide. He was John Brady's best friend and he placed the tricolour on the coffin at the Brady family's request."

Sources said the authorities are aiming to prevent republican paramilitary displays at funerals and events such as Easter commemorations because they are used for propaganda purposes by dissidents.

While the Police Service of Northern Ireland (PSNI) seem unwilling to move in to stop such displays at the time, and can't prove the identity of the masked gunmen, sources said they had adopted a new tactic of charging others present at such commemorations and funerals.

It is understood detectives haven't ruled out arresting and questioning between 50 and 70 other people who were at Brady's funeral.

Sources told the Sunday Tribune that the authorities would present YouTube videos of the funeral as evidence.

It is also understood that two broadcasting corporations have been asked to hand over their footage to detectives. One corporation is reported to have complied while the other is challenging the request.

John Brady was found hanging in a police cell in Derry last October. The authorities claim he killed himself but his family deny this and say his death, which is being investigated by the Police Ombudsman, was highly suspicious.

During Brady's wake, four men in balaclavas and combat gear stood guard over his coffin. Two held .32 handguns and one an AK47. On the morning of the funeral, as the coffin left the house, three masked men with handguns fired a volley of shots. Several hundred people attended the funeral.

Conor Casey, from Cookstown, last week appeared in court to face charges that he did "aid, abet, counsel or procure" the three gunmen on the day of Brady's funeral. He is denying the charges.

Casey's father, Tommy, a Sinn Fein activist, was shot dead by loyalists as he went to check on a neighbour's home in 1990.

Legal sources said that the last time charges followed a republican funeral was after a hunger-striker's funeral in 1981.