Two men and two women have been arrested in London in connection with the murder of Mary Ann Leneghan, British police said today.
A Thames Valley Police spokeswoman said both men had been detained on suspicion of murder, and the women on suspicion of assisting an offender.
All four are being held at police stations across London awaiting interview, she said.
Mary-Ann, whose father is originally from Co Mayo, and her 18-year-old friend, who remains seriously ill in hospital, were abducted by a gang of six men late last Friday night.
They were dumped in Prospect Park, Reading, Berkshire, on Saturday morning after being subjected to a sex attack which lasted several hours. Their attackers had driven them to the Abbey House Hotel, in Connaught Road, before dumping them.