Callous ‘catfish’ killer caught with another phone in prison just months before he’s eligible to apply for parole, Marcus Kirwan, 31, who murdered David Byrne, 19, on March 19, 2011, in Dublin’s south inner city, is now the subject of a new Garda investigation. This is the Fourth time, he has been allegedly caught with a mobile device inside Dublin’s Mountjoy Prison. Kirwan never Showed any Remorse, for the Taking, of a Innocent Teenagers life, a Evil Thug, is Kirwan. Kirwan lost his appeal against the brutal murder in 2015 and is continuing to serve a life sentence.