Susanna Maria Feldman was strangled and buried close to a railway track near a refugee camp in her hometown of Wiesbaden, Germany.
Ali Bashar, 20, was arrested by Kurdish security forces after fleeing Germany to Iraq on a ticket which did not match the name on his passport.
There he was interrogated by Iraqi police officers – where he is said to have confessed to the crimes. He is due to be sent back to Germany today.
This comes after a 13-year-old refugee told police in Wiesbaden that Bashar was responsible for killing the teenager. Bashar is a suspect in a string of other offences, including sexually assaulting an 11-year-old girl in the refugee camp and knifepoint robbery.
He arrived in Germany in 2015 with his parents and five siblings but his asylum request was refused, local media reports. Although he was due to be deported, he obtained temporary residence while he waited for his appeal to be heard.
Susanna went missing on May 23 after going out with her friends the previous night, but police did not investigate because she was “often truant.”
Tributes have now been left near the area she was found – including a cross with a sign reading: ‘Susanna, 14 year-old, victim of tolerance’.
Flowers and candles also adorn the makeshift memorial.
Her mother, Diana Feldman, wrote on Facebook before her daughter’s body was found: “There is nothing worse for a mother in the world than not to know where her child is.”
Now, the case has put renewed pressure on Merkel’s government over the decision to open Germany’s borders at the height of the refuge crisis in 2015.
Alice Weidel, the chief of far right party AfD, told the Times of Israel: “Susanna is a new victim of the egotistical and hypocritical welcoming policy of Chancellor Angela Merkel.”