Lynette White was stabbed over 50 times

Yusef Abdullahi, Tony Paris and Steven Miller - known as the Cardiff Three - spent two years in jail for the murder of Lynette White in 1988 before their conviction was quashed by the Court of Appeal.

Earlier this year, security guard Jeffrey Gafoor was jailed for life after pleading guilty to her murder.

The four - Paul Atkins, Mark Grommek, Angela Psaila and Leanne Vilday - were called to Swansea Police Station on Wednesday where they were formally arrested on suspicion of perverting the course of justice and perjury.

South Wales Police officers carrying out an inquiry into the original trial and investigation said they had sent letters to four people asking them to attend a police station in Swansea.

Gafoor has never spoken about why he murdered Ms White

The inquiry was launched in July following the successful conviction of Gafoor.

Ms White, 20, was stabbed more than 50 times in a flat above a betting shop in Cardiff's docklands on Valentine's Day 1988.

The discovery of her body prompted one of the biggest murder hunts ever mounted by a British police force.

The Cardiff Three were jailed for her murder in 1990 but released on appeal two years later.

It took 15 years to track down Ms White's real killer, but the breakthrough came following advances in DNA technology.

Profile

Following an independent review of the case, a detailed search of the flat uncovered a fresh DNA sample under layers of paint on a skirting board.

Experts were able to find the profile of a person dubbed the "Cellophane Man" because of a bloodstained Cellophane cigarette wrapper found at the scene of the crime.

The profile partially matched that of a youth known to the police, but who had not been born when the murder was committed.

However, he turned out to be a close relative of Gafoor, from Llanharan, south Wales.

They obtained a DNA sample from him which was a perfect match to the one in the flat.

He attempted to commit suicide but was saved by police who broke into his house.

He confessed to the killing, which his barrister told the court that jailed him had been provoked by an argument over payment for sex.