As was expected, he invoked his Fifth Amendment right not to incriminate himself. In fact, Cohen did not appear before the Grand Jury, according to a person familiar with the matter. There was no tactical advantage to bringing him in, this person said, given that Cohen had already communicated to prosecutors his intention not to testify against himself, via his lawyers. In some instances, the government may request that such people appear anyway—but not in this case, the person added.
via SAC Capital’s Steven Cohen Takes the Fifth, From Afar – Businessweek