A Harvard Law School grad accused of torching a 9/11 memorial says someone may have slipped something in his drink and caused him to whack out, his lawyer said.

The lawyer for Brian Schroeder, 26, who spoke at his client’s arraignment last night, added that the whiz kid didn’t even realize that he was targeting a site honoring Sept. 11 victims, although police sources said he made sure to gather many of the teddy bears left by victims’ families to start the fire Saturday at Memorial Park on the East Side.