Police used facial recognition technology to identify and arrest dozens of men allegedly filmed raping a pensioner’s drugged wife, a French court heard on Wednesday.

Dominique Pélicot, 71, is charged with recruiting 50 strangers via an online forum to have intercourse with his wife Gisèle, 72, whom he sedated with powerful tranquillisers in one of the worst rape cases in modern French history.

It came to light by chance when the father of three, a retired employee of the energy supplier EDF, was caught upskirting women in a local supermarket in 2020.

On the third day of the trial in the southern city of Avignon, Jérôme Bosse Platière, the lead investigator, spent a large part of the morning detailing footage of a litany of alleged sexual assault that Pélicot filmed and meticulously stored in computer files under a folder named “abuse”.

There was a sub-folder for each man who came to allegedly rape his wife, these were all under nicknames such as “Chris the fireman”, “Quentin”, “Gaston” and “David the Black”.

Mr Bosse Platière said: “A [police] list was then drawn up for each individual according to the name of the file,” adding that his team worked to identify men behind nicknames.

From a list of 72 individuals suspected of abusing Mrs Pélicot, some 50 suspects, aged between 26 and 74, have so far been identified and tracked down. Most of them face up to 20 years in jail for aggravated rape if convicted.

In order to identify the men, investigators used facial recognition software that “enabled us to identify a third of the perpetrators”, he said.

Investigators sifted through numerous telephone bills, pictures and videos, scrutinising countless telephone exchanges and online conversations between the husband and his wife’s suspected attackers.

Mr Bosse Platière said the police worked to see if there was a link between the calls and instances of alleged rape by looking at Pélicot’s phone bills and the recovered images.

Pélicot had also blocked numerous contacts on his phones, arousing investigators’ suspicions.

“It’s unusual,” Mr Bosse Platière said, adding that it had taken them nearly two years to identify the men behind the phone numbers.

At least 35 defendants have pleaded not guilty and 14 guilty, including Pélicot.

Graphic descriptions of footage viewed by investigators were used in court to counter many defendants’ claims they had not committed rape.

Instead, they claimed to have been taking part in a consensual libertine orgy and that Mrs Pélicot was playing at being asleep.

The court heard that Mrs Pélicot, who remained impassive in court, “snored loudly” throughout most of the rapes and that her husband sometimes made her abusers wait “up to an hour and a half” to ensure she was unconscious, the investigator said.

They were then told to undress in the living room or kitchen “always out of the bedroom” and reminded them to make “no noise, be discreet, very quiet”.

Asked whether Mrs Pélicot was aware of what was going on, Mr Bosse Platière said: “Absolutely not. The victim does not appear conscious in any video,” he said.

The trial continues.