Both are detained under Section 4 of the Criminal Justice Act 1984.
Gardaí at Anglesea Street investigating the murder are appealing to any persons who were in the Bandon Road area between 9.30pm and 10.30pm on Wednesday, September 4.
Gardaí are also appealing to any motorists travelling in the area at that time who may have dashcam footage to make contact.
Investigators say the 55-year-old Mayfield native was killed in his home on Bandon Road and that there were no signs of a break-in.
No weapon has been found, but it is understood that one was used in the murder.
Gardaí said they are not revealing the last place where Mr Jones was seen, or the results of the postmortem, for operational reasons.
Crime investigators have been working at the house to search for clues to help them progress the investigation.
Investigators have asked members of the public who may have seen anything suspicious in the area of Bandon Road/McCurtain Villas between last Monday and Saturday morning to contact them.
Mr Jones, from Cahergal, had been living in the rented property on Bandon Road for a number of years. He was found dead by his son on Saturday morning.