An unemployed Keighley man is standing trial accused of murdering his toddler stepson by throwing him down the stairs more than 23 years ago, after the youngster’s sister recalled the “haunting” memory to a counsellor.

Kerry Harrison was only three years old when, she alleges, she saw Stephen Knox, now of Ingrow Lane, drag her brother up the stairs of their then home and throw him down because he was running around making a noise.

The two-year-old boy died hours later from a brain haemorrhage on December 12, 1986, but Kerry kept the fall secret after Knox allegedly threatened her with the same fate if she told anyone, a Court heard.

It was only after Kerry Harrison, now 26, told her secret to a counsellor in 2007 that police launched a murder investigation, Nottingham Crown Court heard yesterday.

Peter Joyce QC, prosecuting, told the court: “For years Kerry had been haunted terribly by the memory of her brother’s death.

“She recalls Mr Knox hitting Mark which she says was a usual course of conduct. It was about bedtime and Mark was crying. The defendant was hitting him and he grabbed him by the arm and dragged him up the stairs.

“When they got to the top Mark was sent down the stairs, pushed, thrown or kicked. He went all the way down to the bottom and was screaming.”

Mr Joyce added: “Little Kerry was standing at the foot of the stairs when this happened. It was plain to her that Mr Knox realised she had seen what happened. He then threatened her with: ‘If you tell anybody I will do the same to you’.”

Miss Harrison told the court that she, her brother Mark and sister Lesley had moved in to his Leicester house with their mother, Margaret.

Recalling the night Mark suffered the allegedly fatal injuries, Miss Harrison said Knox took a “swipe” at her brother before dragging him upstairs.

“He got to the top and threw him down,” she added. “He just rolled all the way to the bottom. He was screaming and Steve came to take him to bed.”

The boy was discovered lying lifeless and cold in an upstairs bedroom of Knox’s house by three friends after Margaret Harrison went running out of the house screaming for help, the jury heard.

The men called an ambulance and it was then they noticed the couple both smelled of alcohol, the court heard.

Knox would later tell police that Mark fell down three steps, cutting his chin and banging his head.

However, Home Office pathologist Dr Clive Bouch, who conducted the original post mortem examination, said Miss Harrison’s account would explain how Mark suffered previously-unexplained injuries to the back of his head.

Miss Harrison’s counsellor called police and in July, 2007, Knox was arrested on suspicion of murder.

Knox, wearing a dark blue jumper and black trousers, sat through the evidence with an impassive expression.

His barrister, Mark Wall QC, put it to Miss Harrison that she did not remember accurately what happened the night Mark, described as “chubby” and “lively”, allegedly suffered his fatal injury.

He said: “He (Knox) threw toys down the stairs to Mark, didn’t he?”

“No,” replied Miss Harrison.

The barrister continued: “I suggest to you that it was bedtime and Mr Knox started to chase Mark up the stairs, didn’t he?”

“No,” repeated Miss Harrison.

“That Mark slipped and fell down a few stairs?”

“No,” the witness replied.

The trial of 53-year-old Knox was due to continue today.