The man went by the name Uri Brodsky and is believed to be a Mossad agent in Germany who helped create a fake German passport for a member of the Mossad operation in January. He was arrested upon his arrival in Poland due to an arrest warrant issued by Germany.
Notably, Dubai police have stated that he should be prosecuted in Germany where the crime occurred. That is an interesting twist since one would expect that the Dubai police would want to interrogate the man. It may be an effort to reinforce the claim to prosecute the actual hit team members if they are captured. If the man is extradited to Germany without controversy for trial, Dubai would be in a good position to demand the same accommodation for the other suspects.