Friends and family of slain ISIS hostage Kayla Mueller memorialized her at a tearful news conference in her Arizona hometown on Tuesday, just hours after her family released a statement saying the 26-year-old aid worker from Arizona was dead. "The things that were important to Kayla are finally getting the attention they deserve," her aunt Lori Lyon said at the conference in Prescott, Arizona. "We are heartbroken to share that we've received confirmation that Kayla Jean Mueller, has lost her life," Mueller's parents said in the statement released four days after the militant group claimed the Arizona native had been killed by a coalition airstrike near Raqqa, Syria. U.S. officials told NBC News that evidence of Mueller's death consisted of a photograph emailed to the family that "appears to show her dead with trauma injuries," although the injuries did not suggest she had been killed in an airstrike. President Barack Obama expressed his "deepest condolences" on Mueller's death and called her "an outstanding young woman and a great spirit" in an interview with Buzzfeed News Tuesday. "No matter how long it takes, the United States will find and bring to justice the terrorists who are responsible for Kayla's captivity and death," Obama said in a statement. Mueller’s family has released a copy of an unpublished letter she wrote in the spring of 2014 while in captivity.