- Italy and Germany tried to deport Berlin attack suspect Anis Amri
- Deportations can hit roadblocks when countries don't cooperate
(CNN)Two European countries tried to deport him. He served jail time in one of them.
But Anis Amri never got sent back to his home country of Tunisia.
This week, he became Europe's most wanted man after allegedly plowing a truck into a Berlin Christmas market, killing 12 people and injuring dozens of others.
Italian police say they killed the 24-year-old attack suspect in a shootout Friday. But the investigation into his past is far from over.
As details emerge, a key question looms: If Italy and Germany both wanted to deport him, why was Amri still in Europe in the first place?
The case highlights an issue that governments around the world face. Deporting someone -- even a criminal convicted of violent offenses -- is harder than it sounds.
It takes two
The bottom line: In order to deport someone, the person's home country has to cooperate.
In Amri's case, Italian and German officials both say their efforts to deport him ran into roadblocks when it came to getting the documents needed to send him back.
Italian authorities say Amri served four years of jail time for assault, arson and damaging state property at the country's Lampedusa refugee center. They ordered his deportation, Italian state police spokesman Mario Viola said. But Tunisian authorities wouldn't accept the request on the grounds of a lack of proper documentation, Viola said.
Amri was denied asylum in Germany but was not deported because he had no official papers, and his identity could not be determined, officials there said.
Tunisian officials could not be immediately reached for comment on Amri's case.
'Cat and mouse'
In Europe, it's common to hear of cases of immigrants who were ordered to leave but remain, said Demetrios Papademetriou, president of the Migration Policy Institute Europe.
"It's a cat and mouse game that is extremely prevalent between countries who are trying to return nationals to their countries of origin, and countries of origin saying, 'Sorry, does this person have a passport or any other ID that will let us know that, indeed, he's one of ours?' "
For years, he said, European officials have been reluctant to use leverage to pressure other countries to accept deportees.
In Germany, more than half a million people with failed asylum applications who were supposed to leave or be deported remain in the country, Papademetriou said, citing a recent parliamentary inquiry.
"There are probably well over a million people in the European Union who are in the same place," he said.
'Clear public safety threat'
Officials around the world have faced similar predicaments.
In the United States, officials use the term "recalcitrant" to describe countries that won't take back people the US authorities are trying to deport.
There are 23 countries US Immigration and Customs Enforcement describes as recalcitrant, including Afghanistan, Algeria, China, Cuba, Gambia, Iran, Libya, Somalia and Zimbabwe.
"There is a clear public safety threat posed to the United States by the failure of uncooperative or recalcitrant countries to accept the timely return of their nationals who have committed crimes in this country," Daniel Ragsdale, the agency's deputy director, testified earlier this year.
The issue has become a flashpoint for some Republican lawmakers, who've said the United States should fire back by denying visas to countries that refuse to take back their citizens.
This week's attack in Berlin could spur European governments to take a different approach to deportations, Papademetriou said.
Now, he said, they will likely be more willing to use leverage to force home countries to take back deportees.
"It is because of Berlin that I expect things to change. The process is to be accelerated," he said.
Some officials have already been ramping up those efforts, he said, pointing to recent deals the European Union reached with Afghanistan and Mali.
Leaders across Europe are turning more attention to enforcing immigration regulations, Papademetriou said, as they face growing political pressure from far-right groups.
"Clearly," he said, "they have been realizing that they'd better do this, before they start losing elections, big time."