American aid worker Kayla Mueller - who was being held by Islamic State - has died, President Barack Obama has confirmed.
Ms Mueller's family said they were "heartbroken" at the news, and released a copy of a letter she had written in captivity.
Confirmation of Mueller's death comes days after Islamic State claimed the 26-year-old had died in a Jordanian air strike.
The White House and the National Security Council have confirmed they are looking into reports that a female American hostage held by Islamic State has been killed.
A statement purporting to be from Islamic State (IS) claimed the hostage was killed in a Jordanian air strike on a building in the Syrian city of Raqqah, the group's main stronghold, on Friday.
A senior FBI official told NBC News it cannot verify the Isis claim.
Jordan yesterday launched its first retaliatory air strikes against the group since a video showing a Jordanian pilot being burned to death emerged earlier this week.
Following confirmation of the US hostage's death, Kayla Mueller's family have released a copy of a letter she wrote in captivity in 2014.
Here is what we know about American aid worker Kayla Mueller who was being held by Islamic State.