The Garda Commissioner will face strong questioning on the widespread cancellation of 999 calls today.
Drew Harris will appear before the Policing Authority, who ordered an independent review into the controversy.
Up to 500 high-priority crimes, including domestic violence, were not investigated because emergency calls were cancelled.
Sinn Féin's justice spokesperson, Martin Kenny, says there are many unanswered questions.
"I think the first thing we need to hear is exactly what happened, and how and why.
"We need to understand this is not a matter of human error, it was human intent.
"People intended to cancel these calls, have those people been held to account, has the commissioner held them to account in any way?
"I think until we see the full gamut of this report and exactly what's in it, we can't make a decision as to whether or not there should be resignations or if there should be sackings."
