WASHINGTON (AFP) - Warren Weinstein and Giovanni Lo Porto, killed inadvertently in a US strike against Al-Qaeda, were seasoned humanitarians who spent years helping poor communities recover from war and natural disaster.
They were aid workers "who came from different countries but who were united by a spirit of service," said President Barack Obama, who apologised for the mistake.
Weinstein, 73, had two daughters and two grandchildren.
His wife Elaine said he "spent his entire life working to benefit people across the globe and loved the work that he did to make people's lives better."
Weinstein, from the Washington suburb of Rockville, was snatched by Al-Qaeda at night on Aug 13, 2011 in the eastern city of Lahore in Pakistan, only days before he was due to return home to the United States.
He was the country director of US-based consultancy JE Austin Associates, which does contracting work for the US government's development agency USAid.
His wife said Weinstein "loved and respected the Pakistani people and their culture".
"He learned to speak Urdu and did everything he could to show his utmost and profound respect for the region," she said.
As a hostage, he appeared in more than one video released by Al-Qaeda.
In May 2012, he said he had all the medications he needed. Weinstein suffered from asthma, heart problems and high blood pressure.
The White House had said it would not negotiate with Al-Qaeda over the fate of Weinstein, but in August last year Washington made a new appeal for his release.
DEVOTED TO SERVICE
Lo Porto, 39, a native of the Sicilian city of Palermo, devoted his life "to serving others," Italy's Prime Minister Matteo Renzi said.
Lo Porto, known to his friends as Giancarlo, studied international relations in London with a focus on Japan and had worked for aid groups in Croatia, the Central African Republican, Haiti and Pakistan.
He returned to Pakistan on Jan 16, 2012 to lead reconstruction efforts for an area hit by an earthquake and flooding in 2010, as part of a project funded by the European Union. He was kidnapped three days later.
Lo Porto worked for a German non-governmental organisation, Welthungerhilfe, and was abducted in a residence that housed foreign workers in the Pakistani town of Multan, according to Islamabad authorities.
He was kidnapped along with a German colleague.
There was no direct "proof of life" after his kidnapping but there was indirect evidence when his German colleague in a 2012 video suggested he was not alone.
The German was later separated from his Italian colleague and released in October 2014, reportedly after a raid by German special forces.
Marc Gross, spokesman for Welthungerhilfe, told AFP that Lo Porto "knew the region well" having worked in Pakistan for an Italian aid group previously.
In 2010, he had worked to help provide potable water in flooded areas.
"Lo Porto was well known and liked by his colleagues, and this is a very difficult time for us," Gross said.
"His family had not had contact with him for three years, and for them, this is particularly hard."
The Italian daily Corriere della Sera called Lo Porto a "a true volunteer" and "anything but an adventurer."
Obama revealed the deaths of Lo Porto and Weinstein on Thursday in an emotional apology.
The United States was not aware the two men were being held at a location that was targeted in a covert US counter-terrorism "operation" on the Afghanistan-Pakistan border against Al-Qaeda, Obama said.
Elaine Weinstein said that Al-Qaeda bore "ultimate responsibility" for her husband's death, and condemned their "cowardly" actions.
But she said her family was looking forward to seeing the results of a US government investigation into the strike.
She criticised the Pakistani government's attitude toward her husband's case and said assistance from the US government had been "inconsistent and disappointing" over the past three and a half years.