A special garda review team has found 28 cases where homicide investigations by officers were flawed.
According to the Policing Authority, these investigations had at least one issue, ranging from minor to others which were "cause for concern".
The report from the Garda Homicide Investigation Review Team (HIRT) followed a review of 41 homicides from 2013 to 2015, as well as a review of more recent deaths in 2016 to 2019.
Of the 28 incidents identified, 12 included deaths which were mis-classified, where the wrong information entered on Pulse, exhibits were not securely stored and new lines of inquiry were not followed up.
However, these issues did not though impact on the outcome of the investigations in 40 of the cases reviewed, according to the HIRT.
The review team issued 21 recommendations in the report, which the gardaí have said they will implement as soon as possible.
Five have been completed, while a further five will be completed with the next PULSE fix in February 2020.
Outgoing Chair of the Policing Authority, Josephine Feehily, described the report's findings as "inherently worrying".
She said the flawed investigative issues were initially presented by the gardaí as one to do with "boring statistic classifications".
Commenting on the review, Garda Commissioner Drew Harris said the force's main focus was now "to implement the HIRT’s recommendations to ensure public confidence in the quality and standard of garda investigations".
The report came on the same day as Bob Collins was appointed as Ms Feehily's successor as chairperson of the Policing Authority.