Authorities in Antigua say Avie Howell, convicted of the murder of Welsh newlyweds Ben and Catherine Mullany, and another escaped prisoner are considered armed and dangerous and should not be approached.
It is understood Howell is due to stand trial later this year, accused of two other people.
Antiguan police corporal Frankie Thomas assured they were doing all they could to find them.
He said: "We have not yet had any confirmed sightings but we have had a lot of calls from the public. Antigua is a very small island and something does not stay a secret here for long."
"We remain very optimistic and confident we will find Avie Howell."
He urged anyone with information on Howell's whereabouts to contact police.
More top news
Cloud will move away over the evening with clear skies for most, getting frosty later on. Minimum temperature 1°C
Hundreds of protestors opposed to the council's plans to ban dogs from marked sports pitches have marched through the city.
Community groups and third sector organisations have been given the money to help prepare for possible impacts of Brexit.