THE blaze which killed three members of the Sharkey family was set by Robert Jennings on the instructions of Scott Snowden, say prosecutors.

Advocate depute Mr Prentice was giving his closing speech in the fire deaths trial.

Jennings and Snowden deny murdering Thomas Sharkey Snr, his son Thomas Jnr, and daughter Bridget.

They also deny separate charges including fireraising and assault to severe injury.

Thomas Sharkey Jnr, 21, and his eight-year-old sister Bridget died in the blaze at their home in Scott Court in Helensburgh on July 24, 2011. Their father, aged 55, died in hospital days later.

At the High Court in Glasgow Mr Prentice said that there is a repeating pattern woven into the fabric of the evidence.

He said: "One you might not see close up but when you stand back and look at the whole body of evidence like a tapestry, you see it.

"It is this: If you humiliate, cross or even just annoy Scott Snowden he will exact awful revenge upon you.

"The act itself, more often than not, will be committed by Robert Jennings while Scott Snowden has a cast iron alibi."

Mr Prentice told the jurors to ask themsel- ves if the crime was committed and if so were the accused responsible.

He said that the case was a circumstantial one and added: "This can be described as being like the strands of a cable. Each strand may on their own be quite weak, but as they join with other strands the cable gets stronger.

"The more strands you have the stronger it is."

The prosecutor said that the Crown position is that Snowden was in Mexico when the Sharkey fire took place and added that the Crown is asking the jury to find him guilty of acting in concert with Jennings.

Mr Prentice told the jury that the evidence in the trial had lifted the curtain on "a world of violence, intimidation and drug dealing."

Earlier, before the closing speeches began, the trial heard that CCTV footage taken shortly before and after the fatal blaze was not suitable for analysis.

Glasgow Caledonian University lecturer Gordon Burrow, 59, said he was asked by police to examine footage of a person filmed on the streets of Helensburgh.

He said the "blurred" footage made it hard to say what sex the person was.

The trial before Lord Matthews continues.