Police said George Appleton was a serious threat to women
A woman found burnt and strangled made "repeated allegations" about the man detectives believe killed her, the police watchdog has revealed.
The body of George Appleton, 40, was found six days after Clare Wood, 36, was killed in Blackfriars, Salford.
She had contacted police three times about former boyfriend, including claims he sexually assaulted her.
The Independent Police Complaints Commission (IPCC) said Mr Appleton was also known to other police forces.
Mr Appleton was found hanging in a derelict building in Blackfriars last Thursday afternoon.
Greater Manchester Police (GMP) said he was the only suspect in the murder of Ms Wood.
Greater Manchester Police made a referral to the IPCC on 9 February 2009 - three days after Ms Wood's badly burnt body was found at her home.
The IPPC revealed that she alleged Mr Appleton had threatened her and damaged her property on 7 October 2008.
Clare Wood's home was fitted with a police alarm
On 18 January 2009 she alleged that he had sexually assaulted her and Mr Appleton was arrested and later bailed.
Four days later she contacted police again, claiming that Mr Appleton had breached bail conditions by trying to contact her.
Naseem Malik, IPCC Commissioner for the North West, said: "It is evident that Ms Wood was a vulnerable person who had made repeated allegations about Appleton's behaviour towards her.
"Our investigation will examine how Greater Manchester Police dealt with these allegations and whether anything more could, or should, have been done that may have averted the tragic outcome."
Ms Malik said that other women had since come forward with allegations about Mr Appleton, who was also known to other police forces.
Although the investigation is focused on Greater Manchester Police, the scope of the inquiry could be widened.
"It is too early to say whether this will happen, but it is clear our investigation will want to know what information was held by the police in relation to other allegations about Appleton, and whether this should have had a bearing on how Greater Manchester Police dealt with the situation," she added.