Investigations are continuing both north and south of the border into the death of 19 year old Jason McGovern.
The student was found dead at his friend's flat in Emyvale on New Year's Eve.
Post mortem results found he died from severe head injuries.
It's understood the teenager was attacked twice during a night out in Omagh in Co. Tyrone on Sunday - first in a pub on John Street at around midnight - and then outside a nightclub on the Kevlin Road at around 2am.
The PSNI are looking to speak to a man in relation to this alleged assault - he's described as being of stocky built, with ginger or blonde hair.
Omagh Town Councillor Paddy McGowan says vicious assaults are becoming all too common in the town....