A.G.'s office (Mentalist S01E17)

He's from the A.G.'s office. We're catching a hot one.

찾아보니 A.G.는 Attorney General (법무장관, 검찰총장) 을 의미하는 것 같다.

Attorney General

  the most senior legal officer in some countries or states, for example the UK or Canada, who advises the government or head of state on legal matters

  (the Atˌtorney ˈGeneral) the head of the US Department of Justice and a member of the President’s cabinet (= a group of senior politicians who advise the President)