An Old Malden man who took part in a vicious acid attack that left a woman scarred could face extra prison time after a “completely unacceptable” picture surfaced online of him showing off an image of a woman lying on the ground and holding her face.

The image shows Billy Midmore, 23, who was found guilty of inflicting GBH on Carla Whitlock in Southampton in September last year, smiling while holding up a smartphone displaying a picture of a woman clutching her face while lying on the ground.

Prison staff have since raided Midmore’s cell, stripped him of his privileges and placed him in a segregation unit.

He will now face a police investigation which could result in extra prison time.

A Prison Service spokesman said: “This behaviour is completely unacceptable and our thoughts are with the victim of this terrible crime.

“We have carried out a search of this offender’s cell and the social media account has now been removed.

“He has been stripped of his privileges, placed in the segregation unit and faces a police investigation, with the potential of additional time in prison.”

The picture was uploaded to a Facebook profile purporting to be Midmore’s on Wednesday last week.

Offenders are not allowed access to social media sites like Facebook and Twitter while in prison.

It is not known who has been running the account.

An earlier post also showed the results of an online quiz called “Is a serial killer hiding in yourself?” An accompanying comment read: “lol I’ve got big potential”.

Midmore, of Sheephouse Way, was found guilty of GBH with intent after a seven-day trial at Southampton Crown Court in April.

During the trial, jurors heard how the attack was a "debt to be paid" organised by Billy and his brother Geoffrey, both of Sheephouse Way, after Ms Whitlock called asking for £100 of drugs before at least two men met Geoffrey and stole £2,000 of drug money.

The court was also shown CCTV footage of Billy Midmore buying drain cleaner. His brother had described it to him in a text message that read: "This is the one. Face melter.”

Geoffrey Midmore pleaded guilty to the attack at the first opportunity.

Billy Midmore is due to be sentenced at Southampton Crown Court tomorrow.