South Down MP Margaret Ritchie has told the Prime Minister action is now needed after the Loughinisland report.
She says the British government owes survivors and victim's families an apology and justice.
It's on the heels of the findings of a police ombudsman investigation
It documented failings in police handling of the murders of six Catholic men in 1994.
They were killed when UVF loyalists stormed a pub with assault rifles.
No one has been convicted of the killings.
The report in June 2016 showed some officers had colluded with loyalists.
In correspondence with Theresa May, Mrs Ritchie said she's left her in 'absolutely no doubt' of what should happen next.
She's calling for accountability and prosecutions of known suspects in the killings.
Mrs Ritchie also says compensation should be given to the families of the victims and to survivors.
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