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Wenzel from the town of Pulsnitz near Dresden fled a year ago after flying from Frankfurt to Turkey before making her way to Syria.
She then quickly fell in with an ISIS offshoot group before being smuggled into Iraq.
She fell in with ISIS offshoot groups before being smuggled into Iraq Credit: CEN She changed her name to Mariam and sometimes posted photos of herself on her Facebook page wearing a headscarf Credit: CEN Radicalised in Germany, she changed her name to Mariam and sometimes posted photos of herself on her Facebook page wearing a headscarf.
Friends of the teen told police she had suddenly started learning Arabic, taking the Koran to school, wearing conservative clothing and becoming fascinated with Islam before she disappeared.
It was also reported she may have fallen in love with a Muslim boy she met online.
Authorities in Germany, who listed her as a potential terror suspect after her disappearance, confirmed they are examining the new photos to make sure it is actually her.
However, respected newspaper Die Welt, citing security sources, said the captive girl is definitely the missing schoolgirl.
She was among 20 ISIS followers seized after the city fell following a ten month battle which left 25,000 jihadists dead and Iraq's second largest city a sea of devastation.
Mosul lies devastated after being liberated from ISIS fanatics who had held the city since 2014 Credit: AP:Associated Press She was caught in a tunnel system in Mosul with other women, some wearing suicide vests and carrying automatic weapons.
Reports said they worked for the ISIS police force in the city.
Also seized during military mopping-up operations last Thursday were women from Russia, Turkey, Canada and Chechnya.
"There are new findings in the criminal investigation that are being tested," said chief prosecutor Lorenz Haase.
"When she is clearly identified, the investigation will be resumed."
Wenzel was said to be unhappy at home when she turned to Islam.
She soon began engaging with ISIS followers in the Middle East in internet chat rooms and was under the observation of German intelligence officials who suspected her of plotting a serious crime against the state when she fled abroad.
When her mother first noticed she was missing last year the teenager had already flown to Turkey and vanished.
Wenzel's mother said in July last year: "When she did not come back and then I found out she had never even been there, I called the police.
"In her room they found a print of a plane ticket to Istanbul under the mattress. I was shocked, my daughter has never stolen or lied about anything before.
"She got a proper brainwashing I hope we can get her back."