Dereck Chisora returned to England on Sunday after being released without charge by Munich police following his brawl with David Haye.
Chisora, beaten in his WBC heavyweight title challenge by Vitali Klitschko on Saturday night, was freed to return home after earlier being detained at Munich's police headquarters to answer questions about the altercation with Haye which occured during his post-fight press conference.
Chisora arrived on a Lufthansa flight which landed shortly before 2200 GMT at Heathrow, accompanied by Francis Warren, son of promoter Frank Warren.
Chisora passed through the airport without commenting before leaving by car.
The police in Munich remain keen to interview Haye about Saturday night's violent scenes, but the whereabouts of the former WBA heavyweight champion remained a mystery to officers.
Haye could not be found at his hotel on Sunday morning and did not turn up for his scheduled flight.
Haye seemingly threw the first punch in the exchange - with his fist clutching a glass bottle - and was seen trying to hit Chisora's trainer Don Charles with a large camera tripod.
Chisora then repeatedly shouted "I am going to shoot you" at Haye while claiming he had been "glassed".
It is understood officers went to Haye's hotel in the early hours and were knocking on doors and questioning guests in a bid to find the former world heavyweight champion.
It is thought Haye could already be back in Britain having possibly headed home in the immediate aftermath of the incident.
"David Haye is not in his hotel, he is not at the airport," police spokesman Gottfried Schlicht told Sky Sports News. "We don't know where he is.
"We also want to speak to him about what happened last night. We have to hear both sides of the story.
"It's not a charge against David Haye. We have to report everything that happened last night between (Chisora and Haye).
"Maybe he (Haye) has gone home, yes. Then maybe we would talk to our colleagues in Great Britain."
Chisora's promoter Frank Warren was unhappy that the incident took place and, while clearly critical of Chisora's conduct, pointed the finger at former world champion Haye, who had been commentating on the bout.
"It was an embarrassment for British boxing," Warren said.
"I would say they were total idiots.
"(But Chisora) didn't throw the first punch, it's as simple as that. He got hit in the lip with a glass or a bottle, he said.
"I'm sure the police will get to the bottom of it in Germany."
Adam Booth, who was working as a radio summariser and who has trained and managed Haye throughout his career, declined to comment on the incident when contacted.
Chisora clashed with Haye during the post-fight press conference after a slanging match escalated and the two men grappled around the room with their entourages getting involved.
Haye is then captured on video footage trading punches with Charles before swinging the large camera tripod over his head at Charles. Booth suffered a nasty cut on his forehead and also claimed to have been "glassed".
Moments later Chisora reappeared brandishing a glass bottle but was wrestled under control.
Prior to the altercation, the fighters had traded insults, with Chisora mocking Haye's performance in defeat to Wladimir Klitschko last year and Haye responding by pouring scorn on Chisora's record.
Warren was full of praise for his charge's courageous boxing display against the champion but could not hide his disappointment at what followed, and even went as far as questioning whether he could continue as a professional after such events.
"We need to let this sink in, (see) what position he's in and why he's in the position and then we'll deal with it as best we can," Warren said.
"Then we'll decide his future, if he's got a future, in boxing."
British Boxing Board of Control general secretary Robert Smith indicated the governing body would launch an investigation.
"It was extremely disappointing and disgusting, really," Smith said.
"There will be a hearing. I've seen the footage this morning and it doesn't do the sport any good, or Britain. It was like 'Brits abroad'.
"The first thing we need to do is find out the facts.
"I will be contacting the German boxing authorities and now the police to get the facts tomorrow."
Haye does not have a BBBC licence, having officially retired in October, so the governing body is unlikely to be able to sanction him.
However, Smith said Haye's hopes of renewing his licence, if and when he returns to the ring, had "not been helped" by the incident.