Mother Mary Malkin was found strangled in Margate
The man found guilty of murdering disabled Margate mother Mary Malkin nine years ago has had his conviction overturned.
Ms Malkin was found strangled at Invicta House, in Margate, in January 2005.
Her family members in court - including siblings Franky, Johnny and Kathleen - were in tears as the ruling was delivered at the end of a hearing that lasted less than two hours.
Williams was jailed for life in October 2005 and ordered to serve a minimum of 20 years before being considered for parole.
The Court of Appeal hearing followed Williams' application in October 2011 to the Criminal Cases Review Commission (CCRC).
His application was based on new medical evidence that suggested he had been suffering from Alcohol Dependency Syndrome and associated brain damage at the time of Ms Malkin's death.
The court was told by the CCRC legal team that recent CT scans suggested Williams had alcohol-related brain damage.
Dean Williams was convicted in 2005 of murdering his partner Mary Malkin
There was further evidence of organ damage as a result of alcoholism, based on previous medical records.
Reports questioned his mental condition, due to alcohol dependence, at the time of Ms Malkin's death.
"We all assumed that we had justice for our wonderful sister Mary and now here we are about to relive this nightmare again..." - Mary's sister Franky Dillon
Williams, formerly of Millmead Road, Margate, was remanded in custody.
Ms Malkin's sister, Franky Dillon, who now lives in Cork, Ireland, was so upset after the judges' decision was disclosed that she had to leave the court.
She said her family were devastated to be facing a retrial nine years after their sister's death.
She said: "It is very upsetting and painful. Witnesses and statements have got to be redone, a new jury will be brought in.
"We all assumed that we had justice for our wonderful sister Mary and now here we are about to relive this nightmare again."
Franky Dillon, younger sister of murdered Mary Malkin
The family wanted to thank all those who continued to provide "support and kind words" as their grief for the loss of their sister continued.
The Dillon family of six siblings grew up in Thanet. In 2004, the youngest brother Stephen, 26, was killed in a fire following a gas leak at Trinity Square, Margate.
Grief led to his brother Daniel taking his own life - leaving remaining siblings Franky, John and Kathleen.
Ms Malkin's left two sons, Callum and Cameron, who were 16 and 11 when their mother died.
The grave of Mary Malkin, who was strangled in Margate