Ireland’s prime minister has questioned how an eight-year-old boy who may have been killed up to two years ago could have disappeared without being noticed in a case he described as “utterly horrifying”.

Police have taken the unusual step of opening a murder investigation even though no body has been found in the case of Kyran Durnin, who was reported missing along with his mother on 30 August.

Detectives said they were told the pair were last seen two days previously. The boy’s mother has since been located, but police said there was no sign of the child and he was presumed dead.

“Despite extensive enquiries … Garda Síochána (Irish police) have been unable to either locate Kyran, identify any information on his current whereabouts or any evidence that he is currently alive.

“Following enquiries to date investigating Gardaí now believe that Kyran is missing, presumed dead,” the police said, appealing for anyone who has any information that might be connected to the case to contact them.

Police believe he may have disappeared two years ago and said he was known to have been a pupil at a local school until “approximately the end of the 2021/2022 primary school year”.

After obtaining a court order, they began a forensic search of the home and adjacent grounds in Dundalk where Kyran had previously lived.

The case has caused shockwaves across Ireland with the taoiseach, Simon Harris, describing it as “deeply disturbing, deeply upsetting” on Tuesday.

“For any of us as a human being, for any of us parents, to think that a child can effectively disappear and go unnoticed … is utterly heartbreaking and clearly something went extraordinarily wrong here. This child was failed and was failed badly,” Harris said.

“How was this child failed? How could an eight year old little boy effectively disappear and not be noticed?”

Police have stressed that the current tenants of the red-brick terrace house in Dundalk being searched “are not connected in any way with Kyran or his disappearance”. The property was the home of the boy’s family until May this year.

They said they were conducting a forensic search of the house, the garden and adjoining open ground “to discover any evidence which might provide” information about what happened to the child.

Speaking outside Dundalk Garda station, Ch Supt Alan McGovern said police were “liaising closely” with other state agencies including the child protection agency, Tusla.

In a statement, Tusla said that while Kyran was not in their care, its services had engaged with his family with “significant concern” raised in August 2024.

“Since August, we have continued to assist and work closely with the Gardai, and in line with normal practice, all relevant information has been shared,” it said.

The justice minister, Helen McEntee, described the case last week as “devastating”.

“Unfortunately the view is that he is most likely dead and has passed away, but we need to understand what’s happened.

“We need to know have there been failures here, where have those failures been taking taking place, but also who is responsible for them.

“I am absolutely adamant if there were failing here, they need to be addressed and people need to be held accountable.”