A MOTHER of three obsessed with sadomasochism, used her power over men to hatch a plot to assassinate her children's father.

Ex-grammar schoolgirl Tracey Seward wanted Philip Brierley murdered so she could set up home with another boyfriend she met through internet chat lines..

Seward and Swiss national Giona Previtali planned "the perfect murder" after reading a book entitled "Unsolved murders - Dismemberment of bodies".

Security guard Christopher Cassidy was enticed into the murder plot after he was told Mr Brierley had been ill-treating a schoolgirl.

Cassidy finally agreed to be the hit man and after Mr Brierley was lured to a disused garage, he was shot four times in the head at point-blank range with an antique revolver.

After the murder, Previtali, the son of a police commissioner in Lugano, flew to England from his home in Switzerland, and dismembered the body, which was then encased in concrete blocks and thrown in a canal.

Police were eventually alerted because Mr Brierley's family were concerned about his mysterious disappearance and six weeks after the murder, Cassidy finally admitted the gruesome killing.

His confession led to the arrests of 38-year-old Seward and Previtali and last week they are all starting life terms after admitting the murder.

"This is as dramatic and emotionally complicated a murder case as could spring from the most fertile imaginations of dramatists," Judge Sir Rhys Davies told them.

"Fundamental to the case is the compulsive and abusive relationship between you Seward and Brierley.

You are the prime mover but I take a rounded view of the somewhat bizarre circumstances of this case".

"It is a classic case of cold-bloodied murder with malice aforethought".

Alan Conrad QC, prosecuting, said Seward and 42-year-old Mr Brierley had lived together for over 20 years and had a common interest in sadomasochism and sex fetishes.

"It is apparent they were drawn into practices of depravity including crush videos in which small animals and invertebrates are crushed to death for sexual gratification".

After 26-year-old Pervitali was drawn into their perverted world he and Seward started an affair, which led to a series of separations from Brierley, but she would always return to the family home in Arnseby Avenue, Sale.

But she continued the affair with Pervitali, who was then living in England and eventually the couple fled to Northern Ireland after Previtali was beaten up by Brierley.

While in Ireland they read the book about the perfect murder and Seward said they would never be free until Brierley was killed.

Two months later Seward returned to live with Brierley on a trial basis but continued her affair with Previtali and eventually the murder plot was hatched.

"Tracey Seward is a strong-willed, manipulative and cunning woman who can exercise power over men and use it to her own ends," said Mr Conrad.

Seward herself tried unsuccessfully to kill Brierley with sleeping pills and a "campaign of persuasion" was then launched to draw Cassidy into the plan.

Previtali returned to Switzerland and sent Cassidy a package containing an ornamental candleholder with the murder weapon, an antique revolver and 12 bullets, hidden inside the hollow base.

Seward persuaded Brierley to go with her to the disused garage in Cross Street Sale, which Cassidy was guarding.

She feigned a fall and as Brierley leaned over her Cassidy shot him three times in the head.

"Brierley was not dead and Cassidy was about to fire a further shot but was delayed by Seward who appeared to be enjoying his suffering.

But Cassidy then fired the fourth and final shot," said Mr Conrad.

The body was driven to the family home while the garage was cleaned and the gun and shells were thrown into the River Mersey near Sale Water Park.

Previtali arrived from Switzerland the next day and he and Cassidy drove the body back to the garage where Previtali dismembered it.

After the body parts were encased in concrete and thrown into the canal, Previtali flew back to Switzerland and Seward told relatives Brierley had left, taking his fetish clothes with him.

But after Cassidy's confession the concrete blocks were recovered from the canal and a pathologist managed to remove the body parts.

Anthony Berry QC, for Seward, denied she was "a wicked" woman.

"She was more sinned against than a sinner".

He alleged she once fractured her spine after falling when Brierley forced her to climb a tree and he had also caused a miscarriage when he jumped up and down on her stomach.

"She was reduced to long periods of fear and loathing and when she fell in love with Previtali that offered the opportunity to escape from the mental anguish which she had become accustomed".

After the murderers were jailed the victim's sister and brother in law, Christine and Charles Upton said the family was devastated and sickened by the way he was killed.

"Anyone who is capable of such a murder is not human.

This was a cold and callous, brutal murder of a devoted, loving father, brother and uncle".