Seven people were under arrest last night in relation to the shooting.
The bodies of Breda Waters, 28, and Des Kelly, 24, were discovered in a house in Southill in the city on Sunday morning.
The two men captured on CCTV are known associates of the man who ordered the hit, a major crime figure in the city.
It is believed Breda Waters was in the wrong place at the wrong time and that the target was Des Kelly.
The three children of Breda Waters have not yet been told their mother was murdered. Her teenage sister, Tina, said: “We haven’t told them yet what has happened to their mum — we don’t know how we will tell them.”
Tina Waters, 18, was speaking from the family home in St Mary’s Park where Breda’s children — Courtney, 9, Amber, 4, and Jonathan, 2 — are being looked after. She recalled being with her sister at the house in Southill, hours before the weekend double murder of Breda and her boyfriend, Des Kelly.
“I feel terrible, terrible. My heart is broken in two. I’ll never fix my heart again. She was a nice girl to get on with and you’d have great craic off her. She loved to dance and sing. She was like myself. She was a good girl, a good girl with three beautiful children.”
The inquiry last night centred on a high-profile crime figure in the city. Teams of specialist gardaí spent hours searching his house in Limerick’s southside.
The man, however, has no links to the city’s gang feud, but was targeted by a well-known crime family in a number of gun attacks.
Gardaí suspect he may have ordered the murder of Des Kelly over an unpaid debt for drugs.
The man was one of the people who visited the scene of the crime on Sunday morning and publicly sympathised with members of the Kelly family.
Four men and three women arrested yesterday afternoon in connection with the murders were being held in Garda stations in Limerick and Clare last night.
Mr Kelly and Ms Waters died from shots from a shotgun at O’Malley Park where Mr Kelly resided.
Ms Waters, a mother-of-three had only moved into the house in recent days. She was one of a family of 17. In 1997, her brother, Edward, was murdered.
Kelly, who had three children from a previous relationship and had a long history of involvement in serious crime, was jailed in 2004 for four years for driving a stolen car which struck and hit a 15-year-old schoolgirl, Tanya Nunan.
He had only been released after serving his latest jail sentence.
The bodies were discovered at around 11.30am on Sunday morning. Ms Waters was discovered in an upstairs bedroom and Mr Kelly’s body was found lying near a door in a back kitchen.
Gardaí at Roxboro station were alerted by the ambulance control centre who had responded to a call.
More than two shots may have been fired by the killer and at least one cartridge was found on the stairs.
Supt Gilligan said they believe the murders were carried out at around 9am on Sunday morning and two men were involved.
He said they may have left the scene on foot and a burnt-out motorbike discovered in the O’Malley Park area was being technically and physically examined.
He confirmed that a woman and a baby were in the house at 531 O’Malley Park at the time of the shootings. However, it was some hours later when the bodies were discovered.
Supt Gilligan also said they had sealed off another house in Limerick for a detailed forensic examination. On the investigation he said: “There is an air of confidence amongst all our people and more detectives are being brought in from Dublin.”
After State pathologist Dr Marie Cassidy visited the scene yesterday, the bodies were removed at 12.30pm to the Mid-Western Regional Hospital where she later conducted post mortems.
It is believed a number of people in custody were arrested at a similar address.
Searches are still continuing for the gun used in the double murder.