A man has been convicted of murdering a British doctor and his fiancee in their luxury US home – after being thrown out of court for threatening to sexually assault the prosecutor’s wife.

Dr Richard Field, who was originally from London, and his partner, Dr Lina Bolanos, were brutally murdered inside their South Boston penthouse in May 2017.

The couple, who worked as anaesthesiologists, were found tied up with their throats cut.

Bampumim Teixeira, who had worked as a concierge at the building, stood trial accused of two counts of first-degree murder, as well as charges of robbery, kidnapping and “armed home invasion”.

Jurors took less than eight hours of deliberations before returning guilty verdicts, the Suffolk County District Attorney’s Office said.

Following the verdicts, District Attorney Rachael Rollins praised the families of the victims for their “grace, dignity and restraint” after Teixeira “added insult to injury by making outrageous and dishonouring claims”.

During the jury’s deliberations, the 33-year-old defendant had threatened to sexually assault the wife of a prosecutor, telling him: “You better hope I never get out of jail”, NBC Boston reported.

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Bampumim Teixeira is charged with murder while in his hospital bed
May 2017: Bampumim Teixeira was charged in a hospital bed

In another outburst, as the verdicts were read out, Teixeira turned to the sobbing victims’ families and said: “You want to know his last words?”, according to the Boston Herald.

Ms Rollins said: “The defendant’s outbursts today were extremely disrespectful and hurtful to the victims’ families and threatening against the prosecutor and his family.

“These matters will not be taken lightly and I offer my sincere apology that the families had to endure this egregious behaviour.”

Dr Field, 49, and Dr Bolanos, 38, lived together in an 11th floor condominium and Teixeira had used his knowledge of the building to enter through the garage, the court heard.

Richard Field (L) and Lina Bolanos were engaged to be married
Image: Richard Field and Lina Bolanos worked as anaesthesiologists

Police said at the time of the incident that Dr Field texted a friend to report “a gunman in the house” and seek assistance.

Police were alerted and armed officers arrived at the scene, shooting Teixeira twice and wounding him.

After finding the victims’ bodies, police discovered two backpacks at the scene including one which contained jewellery belonging to Dr Bolanos.

The second bag was found where Teixeira was apprehended and contained a replica gun, duct tape with clumps of hair, a knife, a mask and items belonging to the victims.

Dr Lina Bolanos and Dr Richard Field were found dead in the penthouse of the Macallen Building in Boston
Image: Police shot Teixeira twice at the scene

Near the bag, officers also found a large carving knife and a bright yellow shirt, consistent with clothing worn by a person captured on CCTV lurking outside the building’s garage earlier that day.

After the verdicts, Ms Rollins said the families of the victims had been through an “unspeakable tragedy,” adding: “No verdict can ever fill the void created by the violent deaths of Dr Bolanos and Dr Fields, but I hope their loved ones today have a sense of finality knowing that the man who stole these lives has been found guilty.

“He will serve the rest of his natural life behind bars and never again will have the opportunity to harm another member of our community.”

Teixeira is due to be sentenced on Friday.