Baldwin sent a series of texts purporting to be from Jenna

For the 36-year-old factory worker had laid down a financial trail which convinced police experts that he had murdered his stepdaughter Jenna and had used the spade to bury her on a lonely mountainside.

Shortly after Jenna disappeared in September 2002, Baldwin used his cash point card in Pontypool to draw out £10 to buy the spade, but when he visited a local hardware store he found this was not enough.

Inexplicably, he then used his debit card to pay for the £18.95 spade, helping to bring about his own conviction.

But there was no body, and the police still had to treat Jenna as a missing person rather than a murder victim.

In October, there was another development which was to incriminate Baldwin.

A series of phone calls and text messages were sent to relatives purporting to be from Jenna.

Suspicion fell on Baldwin, and from that point onwards, Gwent Police began a cat-and-mouse operation with the man they thought was the murderer.

Baldwin used his Switch card to buy a spade to bury Jenna

The man leading the inquiry, DCI Geoff Ronayne explained: "Few people knew the numbers and we thought the calls were trying to make Jenna appear alive and put us off the scent."

But detectives were on the scent and experts honed in on various phone records, including those of Baldwin who had bought a mobile phone under a false name.

Police experts, helped by the phone providers, traced calls and determined their origin.

Baldwin's clumsy attempts at a cover-up were also discovered when Mrs Baldwin, desperately hoping that her daughter was still alive, replied to a text asking for proof.

She was sent a ring Jenna was wearing at the time she disappeared, but her husband's DNA was found on the piece of jewellery and the envelope by police forensic scientists, further tightening the police dragnet around him.

Surveillance

Still without a body, they had to be careful not to arouse his suspicions and put him on his guard.

"We had to be careful since we knew we had a murderer in that house with two children there as well as Desiree," DCI Ronayne revealed.

"We had surveillance on him 16 hours a day."

As Baldwin tried to cover-up, Jenna was lying in a shallow grave

Through the media, the police were also feeding information to Baldwin in the hope that he would be forced to go to where he had buried Jenna's body.

They hoped he would try to retrieve some evidence, perhaps possessions, which he could use to set up a false trail to show that Jenna was still alive.