This is the moment a secret camera set up by his concerned mother and father captured a care worker hitting their disabled teenager on the back of the head and calling him stupid.

Stanley Nkenka was caught abusing Zak Rowlands, 19, after his concerned parents set up the hidden camera in his bedroom in Oxen Barn Residential Home in Leyland, Lancashire, because he had started flinching when people came near him.

And the fears of Paul and Julie Rowlands were confirmed when they watched the footage and saw their son being hit on the back of his head as he was put to bed before the teenager was left sobbing on his own in the darkness.

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Stanley Nkenka was captured on film hitting disabled Zak Rowlands, 19, at a residential home in Leyland, Lancashire, after Zak's parents set up a hidden camera because they feared the teenager was being abused

Nkenka has been jailed for six months after he pleaded guilty to ill treatment.

In the video clip the 35-year-old is seen hitting the boy on the back of the head and flicking him as he tells him to go to bed. He then pushes the teenager on the bed and says 'it's time to sleep' and calls him a 'stupid boy.'

As the youngster lays in darkness, Nkenka warns him 'Don't come out, or I will hit your head' before he swipes at him again.

Nkenka is seen later approaching Zak and saying quietly: 'Do you want some more?' before he leaves him alone in his bedroom.

Nkenka calls Zak stupid as he puts him to bed and then threatens to hit him if he gets out of his bed again

Zak Rowlands, 19, (left) who cannot speak and suffers with autism and severe learning difficulties, was hit round the head, threatened and then called a 'stupid boy' by carer Stanley Nkenka (right) on his birthday

At the end of the clip the teenager is heard sobbing on his own in the darkness.

Mr Rowlands, a firefighter, told the Daily Mirror: 'Seeing that man do this to my son sent a chill down my spine.

'I felt guilt that I wasn't there for Zak when he needed me most.'

Mr Rowlands said his wife, a police woman, had persuaded him to go through the police rather than confront Nkenka himself. The couple are now campaigning to have cameras installed in all care home bedrooms in a bid to stop patients being abused.

'Sadly we believe this treatment is rife in the care industry,' said Mr Rowlands.

Nkenka is seen helping Zak on with his dressing gown before they go out of the bedroom at Oxen Barn

Nkenka brings Zak back to his bedroom after the teenager had apparently got up and told him to go to bed

As he puts Zak to bed Nkenka calls him stupid and repeatedly says 'down' to get him to move down in bed

The 35-year-old leaves the teenager in the darkness and threatens if he gets up again he will hit him again

He said he felt disabled patients needed property dignity and should therefore have cameras in their rooms to ensure they were not being mistreated.

Oxen Barn - privately run by the Priory Group - is a specialist home for adults who have autistic spectrum disorders and severe learning difficulties. The Priory Group said it had a 'zero tolerance' policy towards abuse and Nkena was sacked immediately after his 'totally unacceptable' actions came to light.

Nkenka, 36, from Bolton, pleaded guilty at Preston Crown Court last month to ill-treatment of a person without mental capacity in the early hours of May 12.

At the hearing Judge Christopher Cornwall said: 'The ill-treatment that is complained of seems to me to be dismissive of him as an individual, unkind and uncaring, and really disrespectful of him as a human being.

'Carers must know that if they fall so far below the standards that are expected of them to the extent that they ill-treat the people they care for, they must know they put their liberty at jeopardy.'

Zak Rowlands' father Paul (left) said Nkenka (right) has damaged the trust they have in the care of their son

When his parents noticed the teenager was flinching, they set up a hidden camera at Oxen Barn care home

Mrs Rowlands previously told the court: 'When I saw the video recording of Nkenka hitting him, I felt sick, heartbroken, angry and incredibly guilty.

'It's hard to articulate the actual words that really describe my emotions. I'm scared, really scared that it will happen again.'

She said she knew something was wrong when her son started to flinch when he was touched or approached.

'Sadly Zak, my loving, affectionate, special and incredibly vulnerable son hasn't the mental capacity to be able to speak but he communicates in his own way,' she told the court.

'By making sounds and by the sparkle in his eyes when he's happy and by the tears and the sorrow in his eyes when he's sad or hurt. But when that's not enough I am my son's voice and will always be until I take my last breath.