British Prime Minister Theresa May has come under increased pressure from just under half her parliamentary group to drop an investigation into the killings of citizens that were not prosecuted or charged during the decades-long sectarian conflict in Northern Ireland

The UK’s Northern Ireland Police Service estimates that 30% of killings during the so-called “Troubles” were covert military operations that took place from the 1960s until the signing of the Good Friday Agreement in April 1998.

The devolved parliament in Northern Ireland agreed in 2014 to set up a unit that would reopen investigations into unaccounted killings that were unaccounted for, which would then lead to possible prosecution.  Roughly a third of these “legacy killings” that are currently under investigation have been attributed to the British security and police forces in their attempts to crack down on Irish republican groups and paramilitary forces, including the IRA.

The so-called Stormont House Agreement was co-signed by the British and Irish Governments and the majority of parties that make up the Northern Ireland Executive.

About a third of these “legacy killings” under investigation is attributed to British security forces. More than 3,500 people were killed in the 30-year conflict between 1968-1998, 52% of whom were civilians, 32% were members of the British security forces, and 16% were members of both Irish Republican and pro-British Unionist paramilitary groups.

A letter signed by 150 Conservative MPs demanded that May show loyalty to the British Armed Forces who served in Northern Ireland during the conflict. The MPs claim May has a duty to protect military veterans from “unfair” prosecution for events dating back decades.

The revocation of an investigative mandate would normally be the prerogative of Northern Ireland’s devolved administration. However, the last unity government in Northern Ireland collapsed in December 2017, leaving the Catholic Irish Republicans and Protestant British Unionists unable to broker a unity government as required by the 1998 Good Friday Agreement.

Given that May’s government depends on the support of the Democratic Unionist Party, her ability to broker a deal based on the Good Friday Agreement has come under intense scrutiny.

According to the BBC, one of the ideas under consideration is to give Britain’s Attorney General Geoffrey Cox a veto over each prosecution, a move that is not guaranteed to pass through the House of Commons.