The family of Lindsay Hawker, the British woman murdered in Tokyo in March 2007, have expressed their anger with the Japanese police for not catching her killer and condemned as a gimmick the latest ruse for solving the crime.

Detectives revealed their new device this week: life-size, talking cardboard cut-outs of the suspected strangler. A button on the back activates a recording of his voice.

The idea is to jog the memory of members of the public who may have encountered Tatsuya Ichihashi, the 30-year-old man who escaped from police moments before they found Ms Hawker’s body in his apartment. But only three of the cut-outs will be visible to the public.

“It would be funny if it wasn’t so tragic,” Ms Hawker’s mother, Julia, said. “At first we thought it seemed like a good idea but when we asked how many there would be, they said five. Two of the cut-outs will be in the police station.

“It was really quite upsetting because it seems that they are no closer to finding him now than when he slipped through their fingers two years ago. We would have respected them more if they’d said honestly to us, ‘We’re doing all we can, but we’re struggling’, instead of trying to appease us with cardboard cut-outs.”

Japanese police used similar tactics in the hunt for three members of the Aum Shinri kyo religious cult suspected of releasing sarin nerve gas on the Tokyo subway in 1995. The fugitives have not yet been caught and their cut-outs lacked the audio component. The one shown to the Hawkers includes a recording found in his personal computer in which Mr Ichihashi, a former student of horticulture, describes a plant.

The case is a grave embarrassment to the Japanese police, who let Mr Ichihashi slip through their fingers after knocking on the door of the apartment where the body of Ms Hawker, 22, was lying in a bathtub filled with soil. Despite distributing tens of thousands of posters, with simulated images showing Mr Ichihashi as he would look dressed in drag or with dyed hair, there has been no confirmed sighting in 19 months. Last year police indignantly denied speculation that Mr Ichihashi had probably committed suicide in some remote spot.

“We have always supported the police, trusted them and given them our support,” said Mrs Hawker, who is in Japan with her husband, Bill, and daughters Lisa and Louise. “But now we are really frustrated and angry and we want some results.”

Ms Hawker disappeared after meeting Mr Ichihashi in a coffee shop near his home in the suburban town of Gyotoku in Chiba Prefecture. He had approached her at a railway station a few days earlier, and followed her to her apartment, eventually persuading her to give him a private English lesson. When friends reported her missing, police visited Mr Ichihashi’s apartment, having found his telephone number on a piece of paper at Ms Hawker’s apartment.

He escaped in his stockinged feet from nine police officers. Afterwards, they found her body in the bath on the balcony. Her hands and ankles had been tied with plastic cord and she was buried in horticultural soil. The post-mortem examination showed that she had been beaten all over her body. Police will not confirm or deny that she was sexually assaulted.

Detective Chief Inspector Ally Wright, a senior murder investigator from the Hawkers’ home county of Warwickshire, has visited Japan and taken part in police raids on 24-hour internet cafés where young homeless people often spend the night.

Mrs Hawker said yesterday: “We will never give up until he’s caught.”

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