A Japanese man accused of raping and murdering British teacher Lindsay Ann Hawker, whose battered body was found in a sand-filled bathtub, Monday admitted the killing but said it was accidental.

Tatsuya Ichihashi, 32 -- who spent more than two and a half years on the run after the 2007 crime and underwent plastic surgery to evade capture -- also admitted to raping his English-language teacher, media reports said.

"I had no intention of murder, but I'm responsible for the death of Ms Lindsay," Ichihashi said on his first day in court, Jiji Press reported. "I'm the one who scared her and left her dead. I'm really, really sorry."

If convicted of murder, Ichihashi could face the death penalty.

As he entered court, the defendant knelt on the floor and deeply bowed twice to the family of Hawker, who had travelled to Japan to attend the trial in Chiba district court outside Tokyo, public broadcaster NHK reported.

Ichihashi, wearing black jeans and a black shirt, stopped short of revealing details of the killing, only saying tearfully: "During the trial, I will speak about what happened."

Six citizen jurors and three professional judges were due to judge the high-profile case under Japan's limited jury system.

Hawker, from Brandon near Coventry, was 22 years old when her body -- battered, naked and bound at the wrists and ankles with plastic cord -- was found in the sand-filled bathtub on the balcony of Ichihashi's apartment.

The autopsy indicated she had died of suffocation.

Ichihashi fled the scene of the crime in Ichikawa, Chiba, and went on the run, working in temporary jobs across the Japanese archipelago, between northern Aomori prefecture and far-southern Okinawa.

He used the money he earned with odd jobs to pay for multiple plastic surgery procedures, altering his eyelids and nose and having a facial mole removed in an effort to change his appearance.

Ichihashi, whose wanted poster was a common sight at police and other public offices across the nation, was caught in November 2009 after a witness tip-off at an Osaka ferry terminal as he tried to catch a boat to Okinawa.

Hawker's parents, Bill and Julia, and her sister Lisa, who arrived in Japan on Sunday, will be allowed to speak as prosecution witnesses during the opening session, and again before sentencing, expected on July 21.

Hawker's family have repeatedly visited Japan and often voiced frustration at police for failing to catch the suspect. Police later raised a cash reward for information leading to his arrest to more than $100,000.

The father said before leaving London's Heathrow airport: "We're a strong family and we're going to see this through to the end. All we want is justice for Lindsay."