A woman in her 50s remains in custody at Letterkenny Garda Station as part of the garda investigation into the death of Seamus Doherty.
The woman was arrested yesterday morning.
A man, aged in his 40s, who was arrested on Wednesday evening has been released.
Both were detained under Section 4 of the Criminal Justice Act, 1984.
Gardaí confirmed that a file is being prepared for the Director of Public Prosecutions.
The body of 67-year-old Seamus Doherty was found at his home in Drumacnoo near Churchill in the early hours of Sunday morning when gardaí and the emergency services responded to a call.
A post-mortem is understood to have revealed that the father of four was strangled.
Gardaí then upgraded their investigation to a murder enquiry.
Anyone with information is asked to contact Letterkenny Garda Station 074 9167100, or the Garda Confidential Line 1800 666 111.