A man suspected of murdering his ex-girlfriend in Greater Manchester was also wanted for questioning over claims he raped her, sources said.
Police made "numerous" attempts to arrest Michael Cope after Linzi Ashton, 25, was interviewed by detectives over the rape allegations.
The mother-of-two also told officers she had been a victim of domestic violence at Cope's hands.
The manhunt for Cope, 28, is continuing after the body of Miss Ashton was found with head and facial injuries at her home in Winton, Salford, on Saturday.
Cope had been in a brief "acrimonious" relationship with the barmaid who worked at the Duke of York pub in nearby Eccles.
Police said local man Cope was still likely to be in Salford and that his family knew officers were looking for him.
Detectives said Miss Ashton was "brutally murdered" and they believe Cope was the man responsible.
The public were told not to approach him and police warned anyone found harbouring or assisting him could expect to be in "very deep trouble".
Greater Manchester Police have referred their previous contact with Miss Ashton to the Independent Police Complaints Commission (IPCC).
Assistant Chief Constable Terry Sweeney said: "As previously stated we know that Michael Cope had been in a relationship with Linzi and through that relationship there have been reports to police in respect of allegations made by her.
"This includes a serious sexual offence and an assault that were reported at the end of April and the middle of May respectively.
"I am not going to go into great detail about these offences or our involvement, suffice it to say Michael Cope was wanted in connection with these matters and numerous attempts were made to arrest him.
"Clearly he is now also wanted for murder, meaning our involvement in relation to these earlier matters will rightly come under enhanced scrutiny and that is why we have made the referral to the IPCC and why we are also reviewing these matters ourselves."
Miss Ashton's body was discovered by a relative at her home in Westbourne Road shortly before 6pm on Saturday.
Her two daughters, Daisy, two, and Destiny, seven, were not at the address at the time.
It is thought Miss Ashton was last seen alive by a friend in the Eccles area shortly before 2am on Saturday.
A large number of floral tributes were left at a police cordon in Westbourne Road and at the pub where she worked in Eccles town centre which was closed over the weekend.
Anyone with information should call police on 101, or Crimestoppers anonymously on 0800 555111.
A Home Office post-mortem examination concluded Miss Ashton died as a result of pressure to the neck and multiple injuries.
Detectives said they are keen to hear from anyone who saw her and Cope together on Friday night.
Chief Superintendent Kevin Mulligan said: "Linzi was beaten to death in a brutal and sustained attack and we are continuing to focus our efforts on locating Michael Cope.
"We believe he is a dangerous and unstable individual and should not be approached.
"I am appealing for anyone who knows where he is hiding to do the right thing and call police.
"We have also established that Linzi and Michael were out together on Friday night and in the early hours of Saturday morning.
"If you were out and saw them together at any point Friday night or Saturday it is vitally important you call the police."