Four people arrested in connection with a Real IRA bomb attack near Claudy in County Londonderry on Wednesday, have been released unconditionally.
A controlled explosion was carried out on a bomb found near a retired doctor's house.
A bomb also exploded outside a Catholic police officer's house on the Ervey Road near Claudy. No-one was injured.
Two men aged 36, one man aged 28, and one woman aged 36, who were arrested have been released.
Earlier this week, police said they had "no doubt" the Real IRA was behind both bomb attacks.
They urged people living in Claudy, Eglinton and the Waterside area of Derry to be extremely vigilant.