Detectives want to speak to possible witnesses seen close to a house where a man was later found dead.
'Four or five' men were seen in the alley between Woolman Road and Clinton Avenue, central Blackpool, at around 10.50pm on Sunday, January 14, police said.
They were heard shouting after a loud bang and 'appeared to be concerned about something', a spokesman for the force said.
Hours later, at around 1.30am on Monday, two hooded figures were seen running down Clinton Avenue towards Costcutter.
Around 45 minutes later, George Crawley, 63, was found dead suffering from head injuries in the back yard of his home in Clinton Avenue.
His housemate, Geoffrey Howard, also 63, was later arrested and charged with wounding with intent. He was remanded in custody.
Det Ch Insp Gareth Willis, of Lancashire Police, said: "The people described in the witness statement were potentially in the area at a crucial time and we’d urge them to contact police. Any information they have could prove useful to our investigation.”
The men are being treated as potential witnesses and not suspects, a spokeswoman for the force confirmed.
Officers have been carrying out door-to-door enquiries in recent days, in Clinton Avenue, Rigby Road, Ashton Road, and Woolman Road.
Det Ch Insp Willis added: "It is important to stress that we are not looking for anybody else in connection with our investigation.
"The purpose of our recent enquiries in the area is to establish if anyone heard or saw anything in the hours leading up to and following Mr Crawley’s death, or knows someone who might have done."
Mr Howard appeared before magistrates in Blackpool on Thursday, January 18, when Howard Green, defending, told the court his client denied wounding with intent.
He was due to face trial at Preston Crown Court, where he was set to appear on Wednesday, February 21.
A post mortem examination found Mr Crawley had head injuries but failed to determine a cause of death.
Information can be reported to police by calling 101, quoting log reference 0069 of January 15.
Crimestoppers can be called anonymously on 0800 555 111.