A grandmother was blasted in the head by the UDA in revenge for her son allegedly providing the drugs which killed a young mum.
Sally Cummins (61) continues to fight for her life in hospital after being hit with shotgun pellets during the attack on her Bushmills Road home in Coleraine.
Her son Russell was also wounded, but his injuries are not life-threatening.
A local UDA unit blamed the 32-year-old criminal for the death of Lindsey Boyd, who was found lying at the bottom of the stairs in the property on September 2.
He denied giving her the drugs that caused a suspected overdose, but that was not enough to save him from last Monday's revenge attack.
Three loyalists surrounded his family home and fired multiple shots through the windows, leaving Sally Cummins, who was not the intended target, in a critical condition in hospital.
Her other son Davy, a convicted murderer who is nearing the end of a life sentence for the 2000 killing of Guy Harper in Portrush, is seeking special leave from prison to be at his mother's bedside.
The 40-year-old is one of the biggest drug dealers in the high-security Maghaberry jail. However, detectives have dismissed that as being a motive for the murder bid.
A security source said: "The UDA gunmen were trying to kill Russell Cummins. They blamed him for causing the death of Lindsey Boyd, who was found dead in the house last month.
"After her body was taken away, 1,000 Xanax (a tranquilliser drug) were discovered in the property."
A police spokesman said detectives were continuing to investigate the circumstances around Lindsey's death.
Her home on Ballygallin Park in the Ballysally estate was searched by the PSNI on Wednesday as part of what was described as a probe into "serious crime in the north-west area". There is no suggestion that any members of her family were involved in the gun attack at the Cummins home or have links to the UDA attackers.
Sources in Coleraine claimed that Russell Cummins' links to local crime figure Peter 'Skeets' Neill Snr provided the UDA with added motive for the gun attack on his home.
A decade ago the 52-year-old identified several loyalists to police who were later jailed for the fatal sectarian assault on his community worker cousin Kevin McDaid.
This turned Neill, who has a lengthy criminal record and was once described in court as a "Mafia Don" and "principal member of an organised crime gang", into a UDA hate figure.
"The UDA was told that the drugs found in Russell Cummins' house had been supplied by Skeets Neill Snr," explained our source.
"This, on top of Lindsey Boyd dying there, led directly to the house being shot up and Sally Cummins being wounded."
But far from the Coleraine UDA leadership being anti-drugs, terrified locals have accused the terror gang's chiefs, who are based in the Harpur's Hill estate, of snorting cocaine and smoking dope.
One resident said: "The overall UDA leader is addicted to steroids and smokes dope all the time. His second-in-command, who is in a loyalist band, is a cocaine addict.
"It makes people sick to see them strutting around saying that they want to protect the community from death dealers when they are taking drugs themselves."
Russell Cummins, the target of the UDA gun gang, is a known drugs user and was previously jailed for six months for getting his mum to smuggle diazepam into Magilligan Prison for him.
She was recorded on CCTV passing her son 98 tablets, which he had arranged to be delivered to her, during a 2013 jail visit.
The grandmother was given a six-month prison sentence, suspended for two years.Stash
Two years later Sally's other druggie son, murderer Davy Cummins, was detained sneaking cannabis and 1,500 diazepam pills into Maghaberry jail after a period of home leave.
He was caught after staff noticed him unsteady on his feet and his lips turning blue. The killer had another 10 months added onto his life sentence for possessing the stash.
Another source who knows the brothers said: "Russell and Davy are two druggies. Sally knows this and has covered for them. That doesn't give the UDA the right to shoot up people's houses. Sally is at death's door because of their stupidity."
Detective Chief Inspector Dunny McCubbin, from the PSNI's Criminal Investigations Branch, explained how the gunmen fired multiple shots through the front and back of the house, hitting Sally in the head.
He said: "They fired through numerous windows indiscriminately, not knowing where the lethal bullets would end up. This clearly highlights the blatant disregard these criminal gangs have for their own community."
The N Antrim/E Londonderry UDA to which the Coleraine UDA belongs split into separate units seven years ago.
Gangs in Coleraine, Ballymoney, Bushmills, Macosquin and Derry act independently from each other, but occasionally unite under the UDA banner.
There is growing unrest about moves into the Dervock area by the West Belfast UDA. Several criminals in the village have aligned themselves to the Shankill Road-based group after being promised protection in return for a cut of drug profits.
This has caused major tension between the N Antrim/E Londonderry UDA and its West Belfast rival.
Northern Ireland Premium
Residents described the horrifying sound of gunshots that left Sally Cummins (61) fighting for her life after being hit in the head during what appeared to be a planned attack on her Coleraine home.