Police arrested a 40-year-old man in Millisle, County Down, on 4 March on suspicion of assisting offenders and withholding information in the murder investigation of Lisa Dorrian.

The 25-year-old from Bangor vanished after a party at Ballyhalbert Caravan Park on 27 February 2005. Officers believe she died that night or in the early hours of 28 February. Her body has not been found.

The man was released on bail. Earlier, on 25 February, a 40-year-old woman was arrested in Bangor and a 42-year-old man in Scotland. Both faced suspicion of murder, assisting offenders, withholding information and preventing a lawful burial. They were released on bail.

Detective Chief Inspector Kerrie Foreman noted the arrest occurred days after the 21st anniversary of the disappearance. She said the family has sought answers for 21 years without success and police remain committed to the case.

Officers asked anyone with information to call 101 or contact Crimestoppers anonymously on 0800 555 111 or online.