CCTV reveals final moments of murdered backpacker

Closed-circuit television pictures that show the last moments of the British backpacker Karen Aim before she was murdered in New Zealand have been released by police.

Ms Aim, 26, was found lying injured in the street in the North Island town of Taupo early on Thursday morning. A murder investigation was immediately launched and a post-mortem examination revealed she had died from "serious head injuries".

The CCTV pictures show Ms Aim, wearing a white top and denim skirt, at a BP service station at around 2am – shortly after she left a nearby bar and half an hour before she was found lying in the street.

Officers have also revealed that, when she was found, Ms Aim was still conscious and was able to tell the police her name. She died later in hospital.

Ms Aim, who is from Orkney, had been in the country since October and was working in a glass-blowing gallery. It was the second time she had visited New Zealand after a three-month stay in 2006. Friends said she "fell in love" with the country.

Her parents, Brian and Peggy Aim, live on the main island of Orkney, and are being comforted by friends. The local population of Orkney is in a state of shock.

More than 50 officers have been drafted in to help in the search for her killer and police have described the case as "a massive whodunnit".

Ms Aim's flatmates have been interviewed by police carrying out the investigation but there are, as yet, no suspects. However, the investigation is focusing on a group which vandalised a nearby college.

Six windows were smashed at the Taupo nui-a-Tia College at around the time that Ms Aim was assaulted, and police are urging them to come forward.

Detective Senior Sergeant Greg Turner said: "The longer those people are at large, the more suspicious it looks for those involved. We would ask again for those people to make contact with us."

As well as canvassing bars in the area, police will also question taxi companies, as they believe Ms Aim took a taxi after leaving a bar.

"We do know that there were two taxis in the area where Karen was found and, as well as the bars, we will be canvassing taxi companies," Mr Turner added.

Police say they also want to speak to anyone who may have visited Taupo, a popular tourist destination, and any of its bars around the time of the attack.

Mr Turner said: "A major focus of the inquiry will be a hotel phase where we will be speaking to bar patrons to try to gather as much information as possible. We're particularly aware of the fluctuation of tourists into the area but need to speak to anyone who may think they have something to add from their time in Taupo, no matter where they are now."

Mystery also surrounds the murder weapon, which the post-mortem failed to identify. Residents living near the scene of the attack are being asked to search their houses and gardens in case a weapon or clothes have been dumped.

Also unexplained is the motive. Officers say there appears to be no sexual motive, although her denim skirt had been disturbed.

A blessing ceremony was due to be held at the crime scene yesterday. A memorial service is planned for next week, with Ms Aim's aunt travelling from Manawatu, an area in the south of North Island, for the church service. Dozens of tributes have been posted on the social networking site Bebo.