That or some other psych med. Trying to avoid prosecution. Going for mentally unfit to stand trial. If he was faking it, it would be spotted sooner or later so he's going with meds. Then after he's found unfit he stops the meds and goes back to living free. The problem with that is that it's not going work. He could be institutionalized until he's fit for trial. If he goes free then he has to worry about street justice. "Poor Joe", he's fucked no matter what he does. Maybe he'll get whacked for knowing too much.