British boxers, David Haye and Dereck Chisora, are suspected of committing offences that could carry prison sentences following their Munich brawl, German prosecutors told BBC Sport.
Haye is suspected of grievous bodily harm – a crime which, if proven, carries a prison sentence of six months to 10 years, prosecutors said.
Chisora is under suspicion of malicious injury, which carries a jail sentence of up to five years, and a “threat”, a lesser offence punishable by a fine or imprisonment of up to one year.
Haye and Chisora clashed after Chisora’s defeat by defending WBC heavyweight champion, Vitali Klitschko, on Saturday night.
Haye said in a statement he would, if requested, “happily assist the boxing authorities with any investigation they wish to launch”.
“I realise I am no angel – and don’t mind a bit of professional trash-talk to help raise boxing’s profile – but, during my 21 years in the sport, I have never been involved in, or even witnessed, such a serious fracas,” he said.
Prosecutors say Haye left the country on a plane before he could be questioned by police.
Chisora and his trainer, Don Charles, were arrested at the city’s airport before being released on Sunday evening. Chisora did not speak to journalists when he arrived back at London’s Heathrow airport on Sunday night.
On top of a police investigation, the British Boxing Board of Control General Secretary, Robert Smith, says Haye and Chisora could face life bans from the sport.
“It’s a possibility,” Smith told BBC Radio 5 live. “The board have many powers. They can fine, they can suspend and they can withdraw a licence.”
The British Boxing Board of Control (BBBofC) said a misconduct investigation had been opened into Chisora’s “behaviour… prior, during and after” the Klitschko fight.
“A further statement will be issued once the stewards have decided on what action will be taken,” the BBBofC said.
“With regard to Mr. David Haye, Mr. Haye is not a licensed boxer with the British Boxing Board of Control and therefore no longer under our jurisdiction.”