Vital evidence not heard during one of the most notorious child murder cases in recent years could prove that the man convicted of the crime is innocent and the true killers are still at large, according to a fresh investigation.

Nine-year-old Zoe Evans disappeared from her home in Warminster, Wiltshire, in the early hours of 11 January 1997 after being tucked up for the night by her mother, Paula.

Despite launching Britain's biggest search for a missing person, it took police six and a half weeks to find Zoe's body, in a badger sett less than half a mile from her home.

The post-mortem found that the child had died from asphyxiation - her T-shirt was pushed into her mouth to stop her screaming.

Miles Evans, Zoe's stepfather, who was 27 at the time of the disappearance, was arrested five days after her disappearance when his bloodied T-shirt was found close to the burial scene. Two weeks later, the former soldier was charged with murder.

Evans has always protested his innocence and, although the Court of Appeal announced last week that it would consider his case, he has continued to insist on a full retrial to clear his name.

According to new evidence to be revealed this week, a retrial may prove that Evans could not have murdered Zoe. The investigation points to two other possible suspects whose names were withheld from the original trial because of lack of evidence. It will attempt to prove that Zoe's body was only placed in the badger sett a few days before it was discovered by police; if successful, it could clear Evans's name.

'The prosecution claimed the six-week delay was because the body was originally fully buried and was only later pulled out by animals,' said Steve McDonnell, editor of the Meridian Television Focus programme, to be screened this week.

But five weeks before the body was discovered, a team of Metropolitan Police officers with dogs trained to search for bodies was told not to look in the area around the badger sett, because it had already been searched.

'Evans's movements from the morning after Zoe's disappearance were fully accounted for,' added Ashton. 'So, if the body was put there after that point, he could not have been responsible for the murder.'

The investigation also found that two youths seen roaming around Warminster on the night of Zoe's disappearance, who were later accused of raping a young woman that same night, could have been near Zoe's home at the time she disappeared.

One, identified as Youth A, had a conviction for indecent assault. When questioned by police shortly after the murder, he denied knowing Zoe but later changed his evidence, conceding that he was familiar with the child because she was a schoolfriend of his sister.

The new investigation has also uncovered two witnesses who did not appear in the original trial. They say they saw two men, one bearing a close similarity to Youth A, disposing of a full bin liner in bushes the morning after Zoe's disappearance.

'The men were acting very suspiciously,' said Loretta Pritchard, a local hairdresser. 'They had a bin liner that they were trying to deposit in the trees and one was walking off while the other was looking around, making sure that no one was watching them.'

She reported her sighting to the police but a brief search by an individual officer found nothing. Five days later, however, Pritchard saw someone resembling Youth A for a second time. 'He came back and deposited something else in the same place,' she said. 'He was very furtive.'

Mike Schwarz, Miles Evans's lawyer, said: 'Evidence has now come to light that poses serious questions about the movements and activities of Youths A and B on the night of Zoe's murder. The jury should have heard about those questions and, if they had done, they might have had another account consistent with Miles Evans's innocence.'

Evans's mother, Sandra, maintains her belief in her son's innocence. 'It takes a very clever person to lie for four years and to keep that lie going and not to crack,' she said. 'I'm his mother and I can say that he's not the brightest person but he has not changed his story from the day he was arrested. That takes a clever person. And I don't think he would be able to do it.'

A former soldier jailed for murdering his stepdaughter has lodged an appeal against his conviction.

Miles Evans, 25, from Wiltshire was found guilty at Bristol Crown Court of killing nine-year-old Zoe in January last year.

Lawyers working for the ex-Army driver have formally lodged their appeal against his conviction to the Appeal Court in London.

He is serving a life sentence for killing Zoe, whose body was found buried in woodland less than a mile from the family's home in Warminster.

The discovery of Zoe's body in January 1997 ended the largest-ever police search for a missing person in Britain.

Evans even made an appeal for her return with his weeping wife at a news conference days after Zoe's disappearance.

The jury at the subsequent trial heard that Evans took the little girl from the family home, punched her face and suffocated her outside.

He then half-buried her in a disused badger sett on Battlesbury Hill, just over half-a-mile from the house.

Police found Zoe's naked and decomposing body six weeks later with her crop top stuffed in her mouth.

Speaking to reporters after the court hearing, Zoe's mother, Paula Hamilton, had said she believed the death penalty for such crimes should be reinstated.

A judge is expected to decide in the early summer if there are sufficient grounds for appeal.

Officers will now work to compile material from the original trial to counter Evans' attempts to overturn the conviction.