Horner is in negotiations with Red Bull over a termination settlement.
The complainant wrote to Red Bull in December 2023 making allegations of sexual harassment and coercive, controlling behaviour against Horner. The allegations became public in February 2024.
Horner has always denied the claims and an internal Red Bull investigation dismissed the allegations on the eve of the 2024 F1 season.
A day later, a tranche of WhatsApp messages purporting to involve Horner was leaked to senior F1 personnel and media.
Horner refused to say whether the messages were genuine, describing them as “anonymous, speculative messages from an unknown source”.
After the complainant appealed about the results of the first investigation, Red Bull launched a second, which came to the same conclusion.
Horner and Red Bull have been approached for comment but have not responded.