Story highlights At least one of those in custody is accused of groping and robbery; at least two are accused of robbery alone, an official says

The Cologne attacks suspects include illegal immigrants and those who've sought asylum in Germany

After the attacks, German officials proposed a plan to make it easier to deport foreigners

Berlin (CNN) Eight men are in pretrial custody in connection with a spate of New Year's Eve mass robberies and sex assaults in Cologne, attacks that spurred a vigorous debate about asylum seekers in Germany.

Ulrich Bremer, the spokesman for the Cologne prosecutor's office, said that at least one of the men in custody is accused of groping and robbery, and at least two are accused of robbery alone. It's not clear what the other five are accused of doing.

Nor were all eight men's immigration status officially known.

But Bremer said 21 suspects originally identified by authorities consisted of some illegally in Germany and some who sought asylum. The latter group included those who've been granted asylum and others waiting for their applications to be granted, the spokesman explained.

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