german authorities knew well before the marketplace attack. according to german investigative files, an informant said amri spoke several times about committing attacks. members of that isis recruiting network backed the idea and discussed driving a truckloaded with a bomb into a crowd. >> the germans dropped the ball here, but in the united states, we have all the lethal attacks in the united states have been by someone who is known by authorities. >> reporter: amri entered italy in 2011 without i.d. he served four years in prison. >> i think this guy looks like a lot of the other murderers we've seen associated with isis in europe. many of them are criminals. they've gone through the prison system, they may have radicalized there. >> reporter: after his release in may of last year, italian police tried to deport him to