The German government can't locate over 160 German "Islamic State" sympathizers who left home to fight with the terrorist organization and may have returned to Germany, according to Welt am Sonntag.

The Federal Ministry of the Interior speculates that most of them were likely killed in combat, but that they could have "succeeded in escaping and/or disappearing" back into the country. The ministry added that it's unlikely that the individuals would pass unnoticed in Germany because of "various measures (including wanted lists or entry bans), which make uncontrolled re-entry much more difficult."

The request for information was made by the Free Democrats (FDP), whose secretary general Linda Teuteberg told Welt that it was highly disturbing that further steps weren't taken to prevent potential ISIS fighters from re-entering Germany "in light of the known patchy protection at the EU's external borders."

Teuteberg added that the government has "no plan for dealing with foreign fighters from Germany" or prosecuting them for their actions.

"This applies to the Germans detained in the conflict zones, as well as the more than 200 former IS supporters who are now back in Germany," she said, adding that German authorities should step up measures to strengthen German authorities' ability to investigate and prosecute war crimes on foreign soil.

In April, German prosecutors charged a 27-year-old German woman was busted by an undercover German security services officer she enlisted to drive her to the Middle East so that she could join up with the Islamic State, which she had been supporting some time. During the drive, she told him all about her time in the organization - which the German recorded.

Identified only as "Jennifer W" due to German privacy laws, she was eventually charged with purchasing a 5-year-old Yazidi girl in Iraq to use as a slave, only to let her die in the scorching heat. American intelligence officials tipped off their German colleagues about the woman, who then set her up with the German driver who she told about "leaving her home in northwestern Germany in August 2014, and making her way through Turkey and Syria to Iraq," according to the New York Times.

Once in Iraq, she joined the Islamic State and "swiftly rose through the ranks, becoming a member of the Hisbah, the morality police, patrolling the parks of the Iraqi cities of Falluja and Mosul."

According to the indictment, Jennifer W. and her husband “bought a 5-year-old girl in summer 2015 from a group of prisoners of war and kept her in their home as a slave.” “After the girl fell ill and wet her mattress, the defendant’s husband punished the girl by chaining her up outside in the searing heat and leaving her in great agony to die of thirst,” prosecutors said. “The defendant let her husband do as he liked, and took no action to save the girl.” Officials have not identified the husband, but German news media have reported he is an ISIS member, believed to be living in the region where Iraq borders Turkey.

"Her job was to make sure that women were upholding the terror organization’s dress and behavior codes," said prosecutors. "To intimidate them, she carried an AK-47 machine gun, a pistol and an explosive vest."