Three dead cats found in Portsmouth - including one with its head cut off - are being linked to the Croydon Cat Killer.
Hampshire Police said they had considered the culprit was the same individual linked to the death of 190 felines in the London area.
The latest discovery was made on April 16 in Southsea, with a further two of the animals found in the Sandown and Isle of Wight regions.
One of the pets was called Poppy and another Fleabags.
"We believe these incidents may be linked to Operation Takahe, a series of cat deaths in the Croydon/M25 area, and is being investigated by the Metropolitan Police Service," an officer said.
South Norwood Animal Rescue and Liberty (Snarl) added that it was possible the Croydon Cat Killer had been holidaying in the area when the animals were mutilated.
Snarl has been documenting the killings and says it has received 230 reports of such deaths, including 40 foxes.
They have been reported predominantly from London, but also as far afield as Birmingham, Manchester, Brackley in Northamptonshire, and Maidstone in Kent.
Boudicca Rising said: "We are very pleased the police are looking at these three deaths."
Referring to the dead cat on the Isle of Wight, she added: "From a post mortem it looked whoever had done it had used a different weapon, but we are keeping an eye on it in case the killer was on holiday and didn't have access to their normal toolkit."
Snarl is advising London cat-owners to keep their pets indoors at night.
Metropolitan Police said in June last year that it had already spent 1,020 hours investigating the deaths since an inquiry was launched in December 2015.