A PSNI detective complained about being asked to investigate a high-profile racist hate crime against a Nigerian man in east Belfast.
Police launched a hate crime probe last year after Michael Abiona found his bungalow covered in banners that read, "local houses for local people".
But internal PSNI correspondence obtained by The Irish News reveals a detective constable bemoaned being asked to investigate.
In an email to colleagues the female officer said: "I have been assigned the above serial for my sins!"
The detective has been spoken to by senior officers over the correspondence.
Alliance East Belfast MLA Chris Lyttle last night described the remarks as "deeply concerning".
He said he would be seeking an "urgent meeting" with the PSNI on the matter.
"This is a deeply concerning insight into the wholly inadequate level of seriousness with which this hate crime was clearly treated," he said.
"It will do little to diminish a perception that police are failing to adequately tackle racially-motivated hate crime and other community relations issues."
There was widespread outrage last year after a group of residents staged a protest outside the Housing Executive property at Glenluce Drive.
Police documents suggest officers monitored the demonstration, recording details such as the number of protesters taking part.
However, no-one was arrested over the high-profile incident and within weeks police said all lines of inquiry had been "exhausted".
PSNI correspondence relating to the protest on June 17 last year was uncovered through a freedom of information request.
Race hate crimes in the north have increased by more than a third in the past year with over 1,300 incidents reported to police during 2014/15.
However, the proportion leading to charges or other actions such as cautions has fallen in the last year, and is considerably lower than for crime overall.
The PSNI's success rate dropped from 17 per cent to 14 per cent over the period, compared to the 28 per cent for overall crime.
An agreed racial equality strategy has still not been published by the Office of the First Minister and Deputy First Minister - almost five years since a panel was launched to oversee it.
Amnesty's Patrick Corrigan said: "It is clear that the PSNI has a lot of work to do to improve the clear-up rate for racially-motivated hate crime and to improve public confidence that they are serious about doing so. This correspondence will do nothing to inspire such confidence.
"Last summer thousands of people took to the streets of Belfast in a demonstration we helped to organise to demand action against racism.
"A year on, we still have no race equality strategy and we still have no sign that the police are being more effective against race hate crime."
Joseph Ricketts, of the African and Caribbean Support Organisation Northern Ireland, said: "We would like to see better accountability and proactive steps taken by all public service providers in targeting and eradicating hate crime.
"A decisive step towards the publication of the Northern Ireland racial equality strategy is now urgently needed."
The PSNI last night said the officer who made the remark has been given "advice and guidance regarding the matter".
Superintendent Robert Singleton said officers pursued a number of lines of inquiry last year including looking for CCTV, door-to-door enquiries and forensics.
"We take hate crime very seriously and actively investigate all incidents reported to us," he said.
"Hate crime is wrong on all levels and the PSNI will do everything it can to ensure that everyone, from whatever background, can live free from prejudice, fear and discrimination."
