Two women are still yet to be formally identified, according to a source at Derbyshire Constabulary and investigators continue to probe the deaths, with no charges yet against the suspect.
But the man in custody has now been confirmed 'arrested on suspicion of murder'.
A spokesperson said: "A man was arrested on suspicion of murder following the discovery of two bodies at a Shirebrook house remains in custody for questioning.
The bodies of two women – believed to be aged in their 50s and 70s – were found at an address in Station Road on Friday evening.
The deaths are being treated as suspicious and a murder inquiry has been launched.
A 20-year-old man from Sheffield was arrested on Saturday and remains in police custody.
Police and paramedics were called to the property on Station Road in Shirebrook, close to the junction with Vernon Street, at about 10.10pm on Friday, February 26, where the bodies of two women were found inside.
Residents told of their spoke following the discovery of the two bodies at a neighbouring house.
Jason Knight, 43, of Station Road, described one of the victims as “a quiet person who kept to herself”.
He added: “This is a nicer area of the town, so it is certainly an unusual thing to happen. There has been nothing like this before.”
“It is very sad."
Another resident, Graham Wheatley, said the first he knew something was wrong was at around 10pm when he saw the police and paramedics arrive.
“It is terrible what has happened,” he said. “We have never come across anything like this before.
“I would see one woman when taking the dogs out. She seemed a nice-enough lady. We said good morning and hello, and she was always polite and friendly.”
Police say officers from Shirebrook Safer Neighbourhood Team will be carrying out high-visibility patrols over the weekend and will be on hand to speak to members of the public.
Anyone with information on the incident should call Derbyshire police on 101, quoting incident number 728 of February 26.
Check back for any news on charges and release of the suspect.