The 67 year old was found dead in the bathroom of his home at Drumacanoo, Glenswilly in the early hours of Sunday morning last.
A man in his 40s was arrested late last night while a woman in her 50s was arrested early this morning.
Both are being detained for questioning at Letterkenny Garda station.
A Garda spokesman said: “Investigating Gardai have made two arrests as part of the investigation into the murder of Seamus Doherty.
“A male aged in his 40s was arrested yesterday evening (20/6/2012) and a female in her 50s was arrested this morning. They are both detained under Section 4 of the Criminal Justice Act, 1984, at Letterkenny Garda Station.”
Mr Doherty, a father of four, was believed to have died of natural causes but this was later upgraded to a murder enquiry after a post mortem by State Pathologist Professor Marie Cassidy on Tuesday.