Candles lit up the plaza of an Arizona courthouse as hundreds gathered to honour the American woman taken hostage by Islamic militants.
Kayla Mueller's death earlier this month was confirmed by her family and US officials.
The 26-year-old international aid worker from Prescott had been captured in Syria in August 2013.
Friends, family and strangers wore pink ribbons on their shirts as they listened to speakers reflect on Ms Mueller's life and work.
Friends and strangers dropped off cards and wrote messages for a scrapbook, calling her an angel and saying she represented the best of humanity.
Ms Mueller's brother, Eric, encouraged the crowd to live as his first friend, best friend and sister did by reaching out to those who are suffering and give them a hug.
His father, Carl Mueller, stood up and met him at the bottom of the stage and hugged him tightly.
"May God keep you from any more harm, any more hurt," Eric Mueller said to his sister.
"You are in his hands now. You do not have to suffer anymore. Only now will you be able to see how much you did and truly did for this world by looking down on it from above."
Ms Mueller's friends set up tables to accept canned goods and monetary donations for the needy, saying that is what she would have wanted.
Rebecca Dunn, who went to school with Ms Mueller in Prescott, said: "She was a saint.
"I'm hoping someone can take on her legacy. There was nothing she couldn't do."
Churches and community groups in Prescott organised the candlelight memorial.
As it opened, a live band sang He Who Began A Good Work In You, a song that Ms Mueller's mother used to sing to her as a child.
The crowd lit candles toward the end of the ceremony on the courthouse plaza and seemingly followed Carl Mueller's lead as he stretched his arm toward the sky.