The US special forces raid targeting ISIS leader Abu Bakr al-Baghdadi was named for Kayla Mueller, a young aid worker who was one of several Americans killed while being held by the ISIS.
Mueller was kidnapped in 2013 in northern Syria during a visit to a hospital. US officials confirmed her death in 2015.
Her father, Carl Mueller, said it had been "a roller coaster of emotions" waiting for President Donald Trump to announce the demise of the man responsible for his daughter's death.
The 26-year-old aid worker was a "beautiful young woman" who died while trying to "help people," Trump said during a news conference announcing the death of the ISIS leader.
"He kept her in captivity for a long period of time. He kept her in captivity, his personal captivity," said Trump.
The White House later announced that the operation to capture or kill Baghdadi had been named in her honor.
"We were deeply touched by what he said. We were grateful that they didn't mess around and went right in," Marsha Mueller, the slain aid worker's mother, told CNN.
Mueller was working for the Danish Refugee Council when she was kidnapped Aleppo.
She was handed over at the end of 2014 to Baghdadi, who is believed to have raped her on numerous occasions.
ISIS said she had been killed near Raqa in February 2015 during an air raid carried out by the US-led international coalition against the terrorists, although the exact circumstances of her death remain unclear.
Her body was never found, leaving a sliver of hope for her parents that she might still be alive.
"Because of that one percent possibility, how do you completely give up until you have her home?" Marsha Moeller told KPHO television in Phoenix, Arizona.
"We want Kayla home, and I know that sounds like an impossible task, but after what we've been through, the things that pop up and happen, I believe we might just find her," she said.
Carl Mueller has told Trump he would be willing to travel to Iraq to try to learn about the fate of his daughter, hoping that lieutenants of Baghdadi who were captured in the raid could shed some light.
"It may be one of these people who were captured yesterday knows what happened and know who killed her," he said.
Trump said during his announcement of the raid that the murders of "the innocent Americans James Foley, Steven Sotloff, Peter Kassig and Kayla Mueller were especially heinous."
Foley, a 40-year-old freelance journalist, was murdered in 2014 in what ISIS said was reprisal for US air raids against it in Iraq. He had been kidnapped in 2012 in northern Syria while covering the uprising against the regime of Syrian leader Bashar al-Assad for the US outlet GlobalPost, AFP and other media.
His mother Diane Foley said Sunday she hoped the death of Baghdadi "will hinder the resurgence of terror groups" and allow captured fighters to be "brought to trial and held accountable."
"I remain concerned about the dozen Americans held hostage in Syria," she added, citing Austin Tice, a US photojournalist taken hostage in 2012, and Majd Kamalmaz, another US citizen seized during a private visit to Damascus in 2017.
"I ask President Trump to make them, and all American hostages, a priority," she said.
Shortly after Foley's killing, ISIS announced it had beheaded another US journalist, 31-year-old Steven Sotloff, who was kidnapped in August 2013 in northern Syria.
In November 2014, ISIS said it had also killed 26-year-old Peter Kassig, an aid worker who had been abducted the previous year in northern Syria. He had served as a soldier in Iraq and had converted to Islam during his captivity.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)