The London Times has been reporting since Sunday that the man is a Slovakian national. An extract from their report this afternoon (behind a paywall):
'Detectives arrested the suspect minutes after he was discharged from a Dublin hospital where he had been receiving medical treatment for injuries consistent with an attempted suicide. The suspect, a father of three who moves between Tullamore and Dublin, had presented himself at the hospital’s accident and emergency department last Thursday evening with injuries to his hands and face. Gardai were alerted as he could not explain how he sustained his injuries.
The arrest followed an analysis of his DNA, which gardai obtained last week when they seized his clothes and medical waste at the hospital using a warrant. The sample was compared against samples left at the scene by the killer. Gardai also collected fingerprints and DNA found on a Falcon Storm mountain bike at the scene.
Gardai had also taken multiple statements from witnesses who identified the suspect as the owner of the bicycle, which had distinctive bright green forks. Several witnesses came forward after gardai released images of the bike as part of a public appeal.
Officers had been tracing the suspect’s movements. Properties in Tullamore and south Dublin were searched last Friday while vehicles and mobile phones were seized. Inquiries had established the man now in custody was present in the Tullamore area on the day of the murder. He was filmed on CCTV cycling a Falcon Storm.
Gardai are continuing to search for a weapon, possibly a knife or a screwdriver, which they believe was used in the attack. Searches continue at the Grand Canal, its hinterland and bottle banks in Tullamore.'