Members of the public out walking were horrified to stumble upon the body of the young man buried in shallow woodland.
It was later identified as Philip Finnegan who had been missing for three weeks from his home in Dublin's south inner city.
The 24-year-old was reportedly wearing the vest because he was living in fear of his life after being targeted by crime gangs in Dublin. His body was found in nearby Rahin Wood last Friday September 2.
A post mortem was carried out overnight but Gardai have declined to disclose the findings, citing operational reasons.
The scene remains sealed off for a technical examination.
An attempt had also been made to set the body on fire as sources said his clothes were charred.
Tributes have poured in for Phillip on social media, the Irish Mirror reports.