The investigation relates to the death of Robert Beattie, 48, who was found with serious burns at his home on Waverley on September 26 this year.
Police believe he had been doused in a flammable liquid when he answered the door of his property, before being set on fire in a targeted attack.
He was taken to hospital but died two weeks later on October 10.
A 25-year-old man from Liverpool was arrested yesterday (December 16) on suspicion of wounding, arson with intent to endanger life and murder.
He has since been bailed pending further enquiries.
DCI Pauline Stables, of Lancashire Police, said: “We have made a number of arrests in connection with our investigation but our enquiries are very much ongoing and we continue to appeal to anyone with information that could help, to come forward.
“This was a horrendous attack on a defenceless man and we believe there will be people out there who will know what happened and who was responsible, and we would urge them to search their consciences and come forward.
“Our thoughts remain very much with Mr Beattie’s family and friends at this sad time.”
Eight men have previously been arrested as part of the investigation, with two having since been released no further action.
The other six men remain on police bail pending further enquiries.
Anybody with information is asked to get in touch on 101, quoting log number 068 of September 26.
Alternatively independent charity Crimestoppers can be contacted anonymously on 0800 555 111 or online at crimestoppers-uk.org.