Detectives searching two properties in Brighton have said that investigations will continue until "all lines of enquiry have been exhausted".
The comments come as it emerged that investigators believe Peter Tobin could be responsible for nine further unsolved murders of young women and girls.
Police have appealed for previous tenants of 67 Station Road, Portslade, to help with their enquiries.
They also want the building company that converted the Seafront Hotel on Marine Parade into bedsits in 1992, to get in touch.
Tobin worked as a caretaker at the Seafront Hotel in the late 1980s.
The itinerant serial killer has lived in several other towns and cities, including Glasgow, Margate in Kent, and Havant, Hampshire, and police are now looking into unsolved murders in these areas.
Police say he may have owned more than 100 vehicles and used 40 aliases.
Detectives attempted to speak to Tobin in prison about the latest developments but he has so far refused to talk.
Tobin was told last December that he would die in jail after he was convicted of strangling 18-year-old Dinah McNicol.
The former church handyman was already serving life terms for the murders of 15-year-old Vicky Hamilton and Angelika Kluk, 23.