FRAMINGHAM — The investigation of the Framingham compounding pharmacy at the center of a nationwide fungal meningitis outbreak has ­expanded to include criminal investigators.

Agents from the Food and Drug Administration were at the offices of New England Compounding Center Tuesday and worked into the evening. They wore blue jackets bearing the yellow letters “FDA OCI,” for the FDA Office of Criminal Investigations, as they went in and out of the brick office building on Waverly Street.