The Shankill Butchers' true leader has been named in a graphic exposé on the UVF and its most notorious sectarian murder gang.
It has been thought for years that psychopath Lenny Murphy headed the serial killers, who committed at least 23 savage murders using butcher knives, axes, guns and bombs during a reign of terror in the darkest days of the Troubles.
But a newly-published book - UVF: Behind The Mask - claims Murphy's older brother John was the real boss.
A woman who claimed she let the Shankill Butchers use her home as a safe house for meetings told author Aaron Edwards that John Murphy was "leader of the pack" in the murder gang.
The west Belfast woman, who is not named, tells Edwards: "They seemed to be scared of John Murphy. They used to blame Lenny.
"They tried to say he gave the orders, but he was in jail most of the time.
"They were that frightened of John".
The woman added she viewed John Murphy as the embodiment of "evilness".
The Shankill Butchers' first victims were four Catholics shot dead in their bottling plant workplace in October 1975.
A month later Frank Crossan (34) was found after Lenny Murphy used a knife to cut his head almost to the spine.
The gang's carnage continued until 1977.
Lenny Murphy was jailed in 1976 for possession of a firearm, but it was thought he made sure the slaughter went on after he directed right-hand-man William Moore, who provided the knives to hack up many more victims, to take over.
But the book claims John Murphy was as feared, manipulative and psychopathic as his younger brother, and was behind the continuation of the sectarian murder frenzy.
The woman who spoke out about the Shankill Butchers using her house for meetings said in the book that John Murphy sat in her front room one evening and told her: "I can't sleep at night. I have to sleep during the day because of all the things I've done."
Lenny Murphy was shot dead by the IRA at the age of 30 in 1982, the same year he'd been released from prison after completing six years of a 12-year sentence.
His brother died 16 years later in 1998 aged 47 in a car crash at the junction of the Grosvenor Road and Westlink in Belfast.
The woman added in Edwards' book: "John got his comeuppance when he hit a roundabout and went through the car windscreen.
"Some people are just evil. There's an evilness there."
It was not until the Shankill Butchers made the mistake of leaving one of their victims for dead that their reign of terror ended.
Gerard McLaverty survived hours of torture involving being stabbed with pokers and knives and being strangled with wire.
He went on to identify his would-be killers and put them in the dock.
The gang was sentenced to 2,000 years in relation to the murders of 19 people, including nine Protestants, who were either mistaken for Catholics or the victims of loyalist in-fighting.
Lenny Murphy was never convicted over any of the murders carried out by the Shankill Butchers.
Edwards is a senior lecturer in defence and international affairs at the Royal Military Academy in Sandhurst.
His book also tells of the never-before-revealed partnership between loyalist terror chiefs Billy Wright and Johnny Adair, and how the UVF once plotted to kill Martin McGuinness.