Gardai are examining a murdered teenager’s phone which they believe could be “key” in the probe.
Investigators are reviewing who Conor O’Brien, who had never come to Garda attention, was in contact with before he was shot dead last week.
They are looking at other devices he used and are interviewing friends and family members as they try to unravel the mystery.
Gardai also believe there were witnesses who could have seen the killer and are working to find them.
Mr O’Brien was found lifeless on Friday outside the self-contained home near where a relative lived in Enfield, Co Meath.
He was blasted once in the chest and cops believe the incident happened on Thursday night.
Originally from Gorey in Wexford, the 19-year-old had moved to the area and only lived there for several months.
He was due to start a year-long blacksmith course next week in Limerick.
Investigators are baffled as to why he was targeted and have “no motive”.
A source said: “This one has really astonished gardai because it makes no sense.
“This was a quiet young lad who had just kept to himself and had never come to Garda attention before.
“A huge inquiry is underway and electronic devices are being looked at.
“Gardai are also talking to his family and friends to see if there was anything whatsoever that might be relevant to the case. But no motive has been established.”
Fianna Fail councillor in Gorey Joe Sullivan knows Mr O’Brien’s family, who he said are “well-respected” in the area.
He told the Irish Mirror: “This is a complete bolt from the blue. That young lad was very quiet. I never heard anything bad about him.
“Nobody has any idea. His life didn’t indicate anything of this nature would happen at all.
“The town is completely shocked and there’s huge sympathy out there for the family.
“Everyone is devastated for them because they are well-known and well-liked.
“And Conor would have had no input into anything that would indicate this terrible tragedy that was to befall him.”
Gorey blacksmith Finin Liam Christie had Mr O’Brien in working with him earlier this month where the teen made two hammers and two sets of tongs.
He told the Irish Mirror: “I’m numb. I sort of know his family, they’re a very good family.
“He was a very quiet guy but a private person. All he wanted to do was blacksmith. It’s so sad.”
The probe has seen a senior investigating officer appointed and an incident room established at Trim Garda station assisted by the Garda National Bureau of Criminal Investigation.
No firearm was recovered at the scene as cops continue to hunt for the killer.
Investigations have determined Mr O’Brien was in contact with a relative at 8pm on Thursday.
Although neighbours heard a single “bang” noise on the night, none reported anything to gardai. CCTV is also being reviewed.
Officers urged anyone who was in the area between 8pm on Thursday and 7am on Friday to make contact.
Supt Liam Geraghty added: “Any person with any information on the fatal shooting of Conor O’ Brien should contact investigating gardai.”
