A GREENOCK man will serve life behind bars after being convicted of murdering his 78-year-old father by strangling him.

John Sharp, 48, from Greenock, throttled his frail dad, who walked with a zimmer, so violently that he shattered a bone in his neck and his Adam's apple.

The brutal attack was sparked by Sharp confronting his OAP dad about why he'd dangled him out a window when he was 15-months-old.

It took place at John Sharp senior's home in Ann Street on January 9.

Sharp claimed that he acted in self-defence and told the jury that his father punched him on the face as he went to leave and then punched him a further three times in the ribcage.

He alleged that he hit his dad in retaliation after becoming angry and then pushed him, causing him to fall into a coffee table.

The killer said he went over and tried to pick up his father, but he was a dead weight.

Sharp claimed the injuries to his father's neck were caused when he lifted him in the choke hold.

Sharp told the jury at the High Court in Glasgow that he and his father argued as they sat having a cup of tea.

He said: “I asked him why when I was 15-months-old he held me outside a window.”

But, the jury rejected his version of events.

Police had rushed to Mr Sharp senior's home when a concerned neighbour dialled 999 after hearing raised voices and a thud.

Sharp brandished a knife at them when he answered the door and Mr Sharp senior was found lying dead in the living room in front of the couch.

His broken dentures were lying nearby.

A pathologist told the murder trial the cause of death was compression of the neck and ischemic heart disease.

Mr Sharp's senior's blood was found on his son's clothes and his DNA was found under the accused's fingernails.

Judge Lady Stacey told Sharp: “There is only one sentence open to me life imprisonment.”

She deferred sentence until next month when she will determine how many years Sharp must serve before being eligible for parole.

Sharp showed no emotion as he was led away to the cells.