A 42-year-old man has been jailed for six months after being convicted of sending menacing online messages to the brothers of a man killed on Bloody Sunday.

Dean Portis, of Olive Street in Derry, made the threats on Facebook during the trial of Soldier F, a former paratrooper accused of murdering William McKinney. The posts appeared above a newspaper image of McKinney’s three brothers, Joe, Mickey and John, attending the Belfast court hearing.

The messages warned of “swift and deadly” consequences if the brothers continued to target the British Armed Forces and the PSNI, and told them they had been warned. John McKinney said in a statement that he feared for his safety and believed he might be watched or followed.

Portis denied the posts were aimed at the family, insisting he intended to create a platform for debate. He was found guilty of two counts of improper use of a public communications network at Belfast Magistrates’ Court.

Deputy District Judge John Rea imposed three months in custody for the offending and activated a previous suspended sentence for a further three months. A two-year restraining order was also granted, prohibiting Portis from contacting the three brothers or journalist Hugh Jordan.

Solicitor Ciaran Shiels, who represented the McKinney family, said victims’ relatives should not have to endure threats from individuals who misuse social media to spread fear and hatred.

William McKinney was 26 when he was shot dead on 30 January 1972, one of 13 people killed when soldiers opened fire on civil rights demonstrators in Derry’s Bogside. Soldier F was later acquitted of his murder.