Catherine and Ben Mullany were shot three weeks ago on their honeymoon.
Two men and a woman are in custody on the Caribbean island of Antigua after being arrested over the murders of Welsh couple Catherine and Ben Mullany.
The doctor and her husband were shot at their hotel on the final day of their two-week honeymoon last month.
Two women have already been charged in relation to stolen goods.
Police in Antigua said their inquiries were continuing and once complete, the director of public prosecutions would be consulted and his advice sought.
The woman now being questioned was detained after the two others, aged 32 and 22, had already been arrested.
The two men in custody are believed to be aged in their late teens or early 20s.
A decision on possible charges could be made on Monday or later in the week.
Inspector Cornelius Charles says Antiguan police and their British counterparts are continuing their inquiry
Police have refused to comment on whether they are confident that any of the suspects in custody will be charged with murder.
A police statement said the arrests had been made as a result of a "proactive police operation" and some of those questioned had been charged with drugs offences unconnected to the murders.
The Mullanys, both 31 and from Pontardawe in the Swansea Valley, were on honeymoon in Antigua when they were shot in their hotel bungalow on 27 July.
The couple were attacked at the Cocos Hotel and Resort, in the south west of the island, in what police think was a robbery which went wrong.
Mrs Mullany died instantly after being shot in the head while her husband, a physiotherapy student, died a week later after he was transferred home to south Wales by air ambulance.
The couple were buried in a private ceremony last week.
The arrests came after two of the women in custody, believed to be accused of handling items which were stolen from the couple, gave the police information.
Antiguan police said the women's arrests and charges were directly linked to the men now in police custody.
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