BERLIN (AP) – The German government pledged Friday to investigate the deportation of a Tunisian man shortly after the deadly 2016 truck rampage on a Berlin Christmas market, but denied media reports that authorities had tried to cover up his possible involvement in the attack.

German weekly Focus reported Friday that Bilel Ben Ammar was arrested days after the market attack and deported to Tunisia a month later, despite having frequent contacts with the attacker.

Tunisian asylum-seeker Anis Amri killed 12 people in the market attack, which was later claimed by the Islamic State group. Amri fled the scene, dying in a shootout with police in Italy days after the attack. Ben Ammar’s current whereabouts are unknown.

German Interior Ministry spokeswoman Eleonore Petermann told reporters in Berlin that deportations “are carried out according to the rule of law and certainly not in order to cover anything up.”

Still, Petermann said Interior Minister Horst Seehofer has ordered a probe into the circumstances of the deportation, which he only learned about on Friday.

The Federal Prosecutor’s Office told The Associated Press it had given the go-ahead for Ammar’s deportation after concluding there was no evidence to charge him with anything in Germany, saying it had considered “all the relevant circumstances.”

“The investigation so far has not revealed that that any suspect – with the exception of Anis Amri – was present at the time of the attack,” the office said.

Still, opposition lawmakers said they want to question Ben Ammar as part of a parliamentary investigation into the attack.

Green party lawmaker Konstantin von Notz said there’s evidence Ben Ammar and Amri met the night before the attack and spoke over the phone on the day it happened.

“The question arises, was he just a witness? Was he an accessory? Or was he a co-conspirator?” von Notz told reporters, adding there are doubts that Amri acted alone.

Focus reported that Ben Ammar was an agent for Morocco’s intelligence service and that the German government may have tried to deport him to avoid him being prosecuted. The magazine claimed that a video, so far kept under wraps by authorities, shows a man who looks like Ben Ammar helping Amri flee the scene of the attack.

Von Notz said lawmakers haven’t been able to obtain such a video. Petermann, the ministry spokeswoman, denied knowledge of its existence.