POLICE hunting the murderer of backpacker Caroline Stuttle are planning a massive series of DNA tests in a bid to track down the killer.

Thousands of young to middle-aged men in the Austra-lian city of Bundaberg will be asked to voluntarily give samples over the next few days.

Miss Stuttle, a 19-year-old from York, had been enjoying a gap year trip to the city, 220 miles north of the Queensland capital of Brisbane, when she was murdered in April this year.

Her body was found under a road bridge over the River Burnett. Her handbag and mobile phone were missing.

Miss Stuttle's father, Alan, 63, of Scarborough, is selling his York art gallery and plans to travel to Bundaberg.

Police believe Miss Stuttle was mugged and then either fell or was pushed from the 65ft bridge. She died from head and spinal injuries.

Inspector Jeff Oliphant said police would do a mail drop next week asking men living on the city's north side to voluntarily provide a cheek swab for DNA testing.

Bundaberg has a population of 45,000, and detectives estimate that several thousand men fall into the testing category.

The decision to carry out mass testing follows analysis of what police believe was saliva found on the bridge where Miss Stuttle died.

Insp Oliphant said that a man seen shadowing her beforehand was walking in the direction of the city's northern district, prompting the decision to target that area.

"He may be a totally innocent person walking across the bridge, but we've just got to try to do something to identify whose sample it is," said Insp Oliphant.

Australia's first mass DNA testing was carried out three years ago. Samples were taken from 600 men at Wee Waa, in New South Wales. The operation resulted in the conviction of a man for the rape of a 91-year-old woman.

Although voluntary, the mass DNA screening prompted criticism from civil liberty groups, which said that anyone who refused to give a sample would immediately be under suspicion.