In a statement, the Parole Board said O’Hara was serving a life sentence when the Board reviewed his case in February 2012 and made a decision to direct his release.
The organisation has pledged a review will examine the decision to release O'Hara from jail.
The Board said it makes its decisions by "assessing the risk the prisoner presents to the public".
It may only direct the release of a life sentence prisoner "if it is satisfied that it is no longer necessary for them to be detained in order to protect the public from harm".
In a statement released by Lancashire Police, the family of Cherylee Shennan said:
The family said Cherylee was a "precious and much-loved" mum, daughter to Betty and Tommy and special step-daughter to Karen and Johnny, sister to Chiyvonne, Ellen, Jordan, Declan and Toni and special aunty to Keilan.
She was a life-long partner to Graham and adoring owner of her five beloved Akita dogs Chan, Diva, Billy, Trooper and Mia.
A man has been sentenced to a whole life prison term after pleading guilty to murdering his former partner in a knife attack outside her home.
Convicted murderer Paul O’Hara, 43, admitted the murder of businesswoman Cherylee Shennan just months after he was freed from jail.
Ms Shannan was knifed 40 times outside her home at Hardman Avenue, Rawtenstall
O’Hara, of Honiton Close, Heywood, was jailed for murder in 1998 and released in 2013.
He admitted the murder of Ms Shannan when he appeared at Preston Crown Court earlier today.
He also admitted charges of section 18 wounding and assault with intent to resist arrest relating to attacks on police officers who had been called to the address.
O’Hara was today given a full life term for the murder of Ms Shennan, who owned a furniture store and a beauty salon.
He was also jailed for ten years for the attack on Det Sgt Damien McAllister and two years for the assault on DC Karen Kenworthy. These will run concurrent to the whole life term.
Ms Shennan, 40, of Hardman Lane, was attacked and killed in the street outside her home on the afternoon of Monday, March 17.
She died at the scene.
A post mortem examination showed she died of multiple stab wounds.
O’Hara was arrested nearby a short time later.
Detective Supt Eddie Thistlethwaite, of Lancashire Constabulary’s Force Major Investigation Team, led the inquiry.
He said: “This was a truly horrendous incident which cost a young woman her life.
“O’Hara is a predatory and violent individual who manipulated his victims including Cherylee, praying on their craving for love and attention.
"He has shown no or little remorse throughout this process and his actions fully justify the sentence which has been imposed.
“I would like to thank the Crown Prosecution Service and Counsel for all their hard work which has resulted in today’s guilty pleas.
"O’Hara’s admission has at least spared the families the ordeal of having to re-live these tragic events through a trial.
“I would also like to praise the bravery of all police officers, PCSOs, and paramedics who attended what was a horrific scene.
"Special thanks must go to Detective Sergeant Damien McAlister and Detective Constable Karen Kenworthy who fought with O’Hara in the vain attempt to save the life of Cherylee.
“Our thoughts and prayers remain with the family and friends of Cherylee. They have shown enormous dignity and bravery throughout this ordeal.”
Sentencing, the recorder of Preston, Judge Russell QC, commended the bravery of Det Sgt McAllister and DC Kenworthy.
The family of a woman killed in Rawtenstall earlier this week have paid tribute to her, calling her a 'precious and much-loved mum'.
Cherylee Shennan was stabbed outside her home on Hardman Lane in Rawtenstall on Monday 17 March.
In a statement her family said:
'Cherylee was a precious and much-loved mum to Lucia, daughter to Betty and Tommy and special step-daughter to Karen and Johnny, sister to Chiyvonne, Ellen, Jordan, Declan and Toni and special aunty to Keilan.
'She was a life-long partner to Graham and adoring owner of her five beloved Akita dogs Chan, Diva, Billy, Trooper and Mia.
We are all devastated that Cherylee has gone. She will be sorely missed but she will always be in our thoughts and in our hearts.'
Paul O’Hara, 41, from Heywood has been charged with her murder. He will appear at Preston Crown Court later today.
A man has appeared in court accused of murdering a woman in Rawtenstall, Lancashire.
Paul O’Hara, 41, from Heywood, appeared at Burnley magistrates accused of murdering Cherylee Shennan.
He has been also been charged with wounding and assaulting two police officers.
He will appear at Preston Crown Court on Thursday, March 20.
Police have released a photo of a woman who was murdered in Lancashire.
Cherylee Shennan was stabbed to death outside her home on Hardman Lane in Rawtenstall on Monday 17 March.
41 year old Paul O’Hara from Heywood has been charged with her murder.
Police have identified a woman murdered in Lancashire as Cherylee Shennan. Ms Shennan, 40, of Hardman Lane in Rawtenstall was attacked and killed in the street outside her home on Monday afternoon.
A post mortem examination carried out yesterday showed she died of multiple stab wounds.
Paul O’Hara, 41, of Honiton Close, Heywood, was last night charged with her murder. He is also charged with GBH 18 and assault with intent to resist arrest. He will appear at Burnley Magistrates Court this morning.
A man has been charged with the murder of a 40-year-old woman, who was found dead in the street in Lancashire on Monday.
Police were called to Hardman Avenue in Rawtenstall after reports a woman had been stabbed.
A 41-year-old man will appear at court later.