THREE knives have been recovered by gardai investigating the brutal stabbing of two German students.
Forensic tests are being carried out on the knives to establish if any of them were used in the killing of Thomas Heinrich (22) and the stabbing of his friend, Robert Rinker (22).
The knives were recovered during a search by officers of the Rialto area of Dublin, close to the Herberton apartment complex where the savage attack happened early on Saturday.
Forensic experts are also analysing blood-stained clothing, also found nearby. Most of it was found in a skip and the tests are expected to determine if it belongs to either of two young suspects, who were questioned about the attack. Officers are satisfied that three local youths were involved in the initial exchange of words with the students.
One teenager, who has been arrested in relation to the killing, is also a suspect for a city-centre bottle attack on two American tourists.
The two Germans were standing on the balcony of their first-floor apartment after a night out when the youths abused them from the pavement. One of them threw an empty beer can at the students.
The Germans went downstairs and after an argument the locals left.
Shortly afterwards two of the three returned, armed with two knives, and began hurling abuse at them again. When the Germans went out to confront them they were attacked with the knives.
Mr Heinrich was stabbed in the stomach and died later in hospital. Mr Rinker sustained injuries to his hands and was also slashed in the side of the head but is recovering from his wounds.
Within hours of the incident gardai arrested a 16-year-old boy from the Rialto area and, shortly afterwards, a 19-year-old was detained when he handed himself into a garda station.
The two were questioned over the weekend and released without charge, pending a file to the Director of Public Prosecutions, who will determine if charges should be brought.
The mother of the younger suspect was also arrested and questioned about allegedly with- holding information but was also released without charge.
Detectives then detained a 19-year-old local teenager, who was suspected of being the third youth involved in the initial exchanges. He was also held for allegedly withholding information and released.
He is also the chief suspect for an attack on two American tourists as they walked alongside the Liffey near Aston Quay earlier this year. They were slashed in the face with a broken bottle.
Gardai questioned the youth about that attack at the time and then sent off a file, which is also under consideration in the DPP's office.
The parents of Mr Heinrich have made the trip from Germany to bring their son home and are said to be "devastated".
Lessons there were suspended to allow students to gather together in their grief. College president Herbert Schmid-Eickhoff also flew into Dublin earlier this week.