Democratic Unionist Party MP Gregory Campbell has warned that the prosecution of British soldiers involved in the Bloody Sunday killings could be “disastrous” for how the legacy of The Troubles is addressed.

The East Derry MP issued his warning following a report that up to 20 retired British soldiers face being arrested and questioned by police for murder as a result of the Bloody Sunday shootings on January 30, 1972.

The Saville inquiry into Bloody Sunday, published three years ago, found that all 14 victims shot dead during the civil rights march in Derry were unarmed and that all the killings were “unjustified and unjustifiable.”

The Sunday Times said some of the soldiers, now in their sixties and seventies, may face prosecution and criminal trials.

It said the British Ministry of Defense had started hiring lawyers to represent the former soldiers.

It could be a year before any soldier is questioned, but the brother of one of the dead victims said the British soldier responsible is a murderer who should already be languishing in jail.

John Kelly, whose brother Michael was one of 14 who died, said the questioning by police should have happened in 2010 following publication of the Saville Report.

He said a soldier who was referred to as F during the Saville inquiry, was responsible for four murders, including that of Michael Kelly.

John Kelly, 64, an education and outreach officer at the Free Derry Museum in the Bogside, said, “I’m looking forward to seeing him being prosecuted. Bloody Sunday was an atrocity, committed by the British Army.”

The Police Service of Northern Ireland said officers plan to question witnesses to the killings, as part of a murder investigation announced by the police in 2012.

Fresh interviews have to be conducted, as police are precluded from using Saville testimony in a criminal investigation.

In an official statement, a PSNI spokesman said, “Preliminary work has begun into what will be a lengthy and complex investigation into the events of January 30, 1972.

“For the investigation to be as comprehensive and effective as possible, police will be asking for public support in the form of witnesses who gave evidence to the Saville Inquiry now making statements to detectives.”

The inquiry by High Court judge Lord Saville was the longest and most expensive in British legal history.

It lasted 12 years and concluded that there was no justification for the shootings, prompting British Prime Minister David Cameron to apologize for the killings.