A teenager, who was questioned by gardaí investigating the fatal stabbing of a German student in Dublin, has been released without charge.

He was arrested last night in relation to the incident on Saturday morning at the Herberton Apartments in Rialto.

Three other people who were being questioned in connection with the attack have also been released without charge.

Thomas Heinrich, 22, from Munich, was studying international media in Dublin for the past three months.

He was on the balcony of his first floor apartment with his German flatmate when words were exchanged with two teenagers walking on the street below.

An altercation broke out and Mr Heinrich sustained serious stab wounds to the stomach, and his friend was stabbed at least five times.

Both men were brought to St James's Hospital where Mr Heinrich later died.

The second man remains in a critical condition.

Over the weekend, a 15-year-old boy and 19-year-old man were questioned by gardaí in relation to the knife attack, while a woman in her 40s was detained on suspicion of withholding information.

Gardaí have appealed for witnesses or anyone with information to contact them.