Officers in London investigating the murder of Mary-Ann Leneghan whose family come from Bangor Erris, Co Mayo, arrested a man in his 20s yesterday, Thames Valley Police said.
The suspect, arrested in London, is the fifth person to be held. Sixteen-year-old Mary-Ann, from Reading, Berkshire, died from a stab wound to the neck.
Her friend, who cannot be identified, is in hospital after being shot and stabbed. Both teenagers were sexually and physically assaulted by a gang of at least six men.
The young women suffered a "disgusting ordeal" lasting several hours at the hands of up to six attackers, police said. The second girl is a key witness and is helping police with their inquiries from her hospital bed where she is in a serious but stable condition. Supt Dilip Amin said it was "very fortunate she was still alive". He said: "She is very ill from the injuries she has received, but she has been very brave in helping police."
Police believe the two young women may have been deliberately targeted, though they were not able to confirm whether the attackers were known to their victims. They were finally left at a remote spot in Prospect Park in Reading.
The 18-year-old managed to make her way to a nearby road and flag down a passing motorist. Mary-Ann's body was discovered in the park by police at 5.30am. Detectives arrested another man in his 20s yesterday at a south London address but he was later released on bail until June 2nd by Thames Valley Police. Supt Amin said last night: "Information we have suggests that this is not a random attack. We are keeping all our options open as to what the motive was."
The pair's ordeal began between 10pm and 11pm on Friday evening when they were approached by a group of men in a car park near a derelict pub in Reading. They were taken by car to a guest house in the red light district of Reading at 1am.
The vehicle, being driven erratically and at speed with loud music blaring, left the guest house between 3am and 5am.
CCTV footage is being scrutinised to trace the vehicle. Officers believe that it was at the guest house that the girls were subjected to numerous "horrific and terrifying" assaults.