The photos were printed in two publications in September, one of which displayed shots of the former Kate Middleton half-naked having suncream rubbed into her buttocks by William at a private chateau in the south of France.
The grainy snaps triggered an immediate furore in Britain, and the angry royal couple launched legal proceedings in France.
According to sources close to the case, the head of the Mondadori Group – which publishes glossy French magazine Closer – and a photographer at daily La Provence were both charged with "invasion of privacy" earlier this month.
Judges in the Paris suburb of Nanterre charged Ernesto Mauri, chief executive of Mondadori, for having allowed the topless shots to be published in Closer on September 14th. The identity of the paparazzi who took the photos remains a mystery.
Photographer Valerie Suau, meanwhile, was charged for taking photos of the Duchess of Cambridge in a swimsuit in the same place, which were printed in La Provence a week earlier on September 7th.
The royal couple's lawyer Aurelien Hamelle, Mondadori and La Provence all refused to comment when contacted by AFP.
The pictures were taken when the royals were vacationing in southern France at a chateau owned by Viscount Linley, the son of Princess Margaret, the deceased sister of Britain's Queen Elizabeth II.
The royal couple launched legal proceedings soon after they were published, with their lawyer arguing that the images were particularly distressing in light of William's mother Princess Diana's 1997 death in a car crash while being pursued by paparazzi.
French authorities promptly banned Closer from any further publication or resale of the pictures, while launching a criminal probe into how they were obtained.
But the topless photos still appeared in magazines in Denmark and Sweden, Ireland's Daily Star and Italy's Chi, which, like Closer, is owned by Mondadori.
Chi produced a special edition featuring the grainy photos along with a series of articles on topics such as "Kate's breasts, natural or fake?"
The magazine's editor Alfonso Signorini argued in the special edition that the pictures represented an "extraordinary reportage".
"For the first time, the future queen of England was appearing in a natural way, without the constraints of etiquette," he wrote.
In 2006, Chi sparked outrage in Britain when it printed a photo of a fatally injured Princess Diana being given oxygen at the scene of the 1997 Paris crash, together with details from her autopsy.
Closer magazine has said its editor Laurence Pieau received death threats for publishing the topless photographs. After publication, Pieau had defended them saying they were not in the "least shocking".
The magazine has refused to say from whom it bought them or who the photographer is.
But French celebrity photographer Pascal Rostain, who has had several scoops, told AFP the snaps were taken by an Irish photographer.
About the photographer's identity, he said: "In our small paparazzi world, we know who it is but obviously don't say anything.
"I can just say it is an Irish national who lives in the south of France," he said.