Catherine and Benjamin Mullany were attacked on honeymoon
A police chief says he is confident of catching a gunman who killed a bride and left her new husband in a coma on their honeymoon in the Caribbean.
Antigua police commissioner Gary Nelson says a "person of interest" is being interviewed about the shooting of Benjamin and Catherine Mullany.
Mr Mullany is in a Swansea hospital, where doctors will consider brain stem testing if he remains in a coma.
His wife's body has also been flown home, six days after the attack.
The couple, both 31 and from Pontardawe, Swansea Valley, were attacked on Sunday, the last day of their two-week honeymoon.
We are turning over all the stones to find the person responsible
Gary Nelson, Antigua police commissioner
Mr Nelson said the shooting was similar to another murder in the capital, St John's, two months ago and he thought they could be connected.
That also appeared to be a robbery, and the young male victim was shot in the back of his head.
"I like to say we are doing it by the numbers, and now we might be in for the long haul," he told the BBC News Channel. "We are turning over all the stones to find the person responsible."
Asked if he expected to catch the killer, he said: "I'm confident. We are not going to stop.
Antigua police chief on the murder investigation
"We have another homicide - I think they are linked, but they may not be. I've met the family and gosh, it was hard, it was tough.
"Some of the toughest things a police officer can do is talk to the family of the victim. It's so sad."
Mr Nelson has also said the police were being hampered by a "code of silence" or lack of trust in police on the island.
"People don't want to tell the police (anything)," he said.
A reward of £67,000 has been offered for information leading to the conviction of the killer.
Mr Nelson, who was brought in from Canada earlier this year, is in charge of a 350-strong police force which operates with no computers and no crime database, and only one forensics officer.
Police have now questioned more than 30 people in the investigation.
Mr Mullany, a third-year physiotherapy student at the University of the West of England (UWE) in Bristol, is being treated at Morriston Hospital in Swansea, where his late wife had trained.
He has a fractured skull and a bullet lodged in the back of his head.
Marilyn and Cynlais Mullany listen to Dr Pushpiner Mangat at Morriston Hospital
Dr Pushpiner Mangat, the hospital's clinical director for critical care, told a press conference: "Ben remains critically ill. He has not required sedative drugs at any time over the last 24 hours, yet remains in a coma."
Dr Mangat said that if 31-year-old Mr Mullany remained in a coma it was likely doctors would proceed to brain stem testing.
Dr Mangat said "predictable abnormalities" were found involving his blood chemistry and temperature, and treatment was continuing to deal with these.
Mr Mullany's parents Cynlais and Marilyn, who live close to the hospital, attended the briefing but did not speak and no questions were allowed.
"It is poignant that Ben is being cared for in the intensive care unit where his wife, Catherine, had recently worked during her training to become a GP," said Dr Mangat.
"Staff at the unit, and across the trust, have been shocked and devastated by the tragic events in Antigua.
British officers will fly to Antigua to help Antigua police with the investigation. Scotland Yard is sending a team following a request from Mr Nelson, and it will include one officer from South Wales Police.
Mr Mullany's flight landed at Cardiff International Airport in the early hours and was then transferred by ambulance, with a police escort, to Morriston Hospital.
The body of Mrs Mullany was accompanied home by her parents, and arrived at Gatwick airport a couple of hours later.
The couple were shot in a suspected bungled robbery at the Cocos Hotel.
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