“Serial philanderer” Peter Wallner, 35, was sentenced to a minimum of 20 years in prison after an Old Bailey jury last Friday found him guilty of murdering his wife at their home in Hamilton Avenue, Cobham, four years ago.

He always claimed his wife’s death was a tragic accident during a violent late-night row.

But the jury decided he cold-bloodedly murdered South African Melanie Wallner, 30, hitting her in the face with a heavy Le Creuset pan three times, most likely killing her while she was asleep or resting wearing an eye-mask, before he put a plastic bag over her head and ran her body under the shower.

The German chef then wrapped her body in a sleeping bag, placed her in a storage room and started spreading lies about her death.

When asked about what he did that night, and how a plastic bag and eye mask came to be on his wife’s head, he repeatedly claimed he did not remember because it was four years ago.

But why, after successfully maintaining his lie for three years, did he finally dump her body in the wheelie bin, giving the game away?

Other murderers have disposed of bodies in numerous inventive ways and for much of the time he was alone in the house, despite his overlapping affairs with women including a police worker.

One neighbour, who asked not to be named, said: "It doesn’t make sense but only he would have the answer to that question.

"Did he panic at the last minute?

"It is a good thing he did else he could have got away with it."

Surrey detectives, including Maria Woodall, who is also investigating the Milly Dowler killing, are convinced he believed the bin-men would not notice.

The jury was shown a video of the bins being emptied straight into the truck, and was told he hoped to get away with murder.

Wallner claimed he knew he was on borrowed time from the moment she died and pointed to his suicide attempts as evidence he became fatalistic about his chances of evasion.

But prosecutors pointed to his flight to Malta, his continued lies, and his complete lack of remorse, as well as his attempt to avoid incriminating questions by claiming memory loss.

Only Peter Wallner knows why he killed Melanie, why he kept up his charade for so long only to blow it with an apparent act of panic that sowed the seeds of his capture and eventual life sentence.