The garda ombudsman commission is examining the scene where a teenager died in County Waterford, following an earlier assault on an off-duty senior Garda at his home.
The officer went to the door at around midnight after being alerted by a noise.
He was injured when a bottle was thrown at his head after confronting a group of young men outside.
The men fled - and while an 18 year old was making his escape, he sustained fatal injuries after climbing along a high fence and ending up in a stream.
A post mortem is to be carried out to find out exactly how he died.
Three others were arrested in follow up searches.