A British-born doctor killed alongside his anaesthetist fiancee in their luxury US penthouse has been described as "tremendous" by colleagues.
Anaesthetist Richard Field, 49, and Lina Bolanos, 38, were found dead in the apartment in Boston, Massachusetts, on Friday night.
During his final moments Dr Field had texted a friend to report a "serious situation" with a gunman in his home, according to prosecutors.
And in startling scenes on Monday their alleged murderer was charged before a robed judge while still in his hospital bed as he recovered after being shot by police.
A Facebook profile belonging to Dr Field says he was from the United Kingdom, while it has been reported he was born in Hammersmith, west London.
According to the Massachusetts medicine board he graduated from Sheffield University in 1999 and worked at a clinic in Beverly, north of Boston.
The North Shore Pain Management centre, where he had worked since 2010, spoke of him as a "guiding vision" who gave patients and colleagues his "tireless devotion".
"He was a valued member of the medical community and a tremendous advocate for his patients," a Facebook post said.
"His tragic and sudden passing leaves an inescapable void in all of us."
Paying tribute, one patient wrote on Facebook: "He was an amazing Dr. who was so kind and compassionate.
"I always said if he ever moved back to England I would follow him. Dr Field changed my life."
Dr Bolanos worked at Massachusetts Eye and Ear hospital as a paediatric anaesthetist and was an instructor at the Harvard Medical School.
John Fernandez, the hospital's president, said: "Dr Bolanos was an outstanding paediatric anaesthetist and a wonderful colleague in the prime of both her career and life."
The couple were found dead in the apartment having suffered "obvious trauma", the Suffolk County District Attorney's office said.
On Monday Bampumim Teixeira, a 30-year-old with two previous convictions of demanding money from banks, was charged with two counts of murder.
He was shot three times when police arrived at the scene where they found a backpack full of jewellery, a replica firearm and at least one knife.
Boston Police said they were called by the apartment block's front desk at 8.40pm.
"The caller stated that another party had alerted him to a text requesting police notification for a 'serious situation' with a gunman in the victims' apartment," Suffolk County District Attorney's office said.
When officers arrived at Dr Field's 11th floor apartment they found a set of keys outside the door and warned the police had arrived.
The prosecutor continued: "The officers entered to perform a protective sweep of the darkened residence and soon encountered an unknown person – later identified as Teixeira – wearing dark clothing.
"Believing this person either pointed or fired a weapon at them, two officers discharged their own weapons and struck him in the hand, abdomen, and leg.
"The officers provided first aid to Teixeira outside the apartment, where he allegedly stated that another person would open fire on the officers if they went back inside."
The suspect, of nearby Chelsea, had recently been released from jail, having passed notes demanding money from a bank on two occasions, according to prosecutors.
Teixeira's lawyer, Steven Sack, entered not guilty pleas to the two counts of murder at South Boston Municipal Court and did not request bail.
The case returns to court on June 8.