PARIS — A prosecutor’s office says a French judge has placed under investigation the photographer and publishing company behind unauthorized topless photos of Prince William’s wife, Kate, that appeared in “Closer” magazine in France last September.

Caroline Chassain, spokeswoman for the Nanterre prosecutor, said Thursday that a photographer, the newspaper La Provence — the photographer’s employer — and Mondadori Magazines France were placed under investigation this month over possible criminal exploitation of images.

It could still take months before a decision is made whether to charge them as part of the criminal investigation into the case involving the British royals.

The blurry photos of the Duchess of Cambridge have been called a grotesque abuse of privacy by British royal officials.