THE convictions of two Middlesbrough brothers for the murder of a well-known Teesside hardman are "unsafe" and should be quashed, the Court of Appeal was told today.

David and Terry Reed, of Tennyson Avenue, Grangetown, are challenging their convictions for murdering 43-year-old former boxer Peter Hoe at his home in Jubilee Road, Eston, near Middlesbrough, in October 2006.

Lawyers for the pair, who are serving life sentences, say the way DNA evidence was dealt with at Teesside Crown Court in August 2007 was wrong and should result in their convictions being quashed.

James Hill QC, representing David Reed, 31, but whose arguments also relate to his 28-year-old brother, told how they had been linked to the murder after their DNA was found on plastic splinters, most likely from knives, lying beside the body.

At the trial, a Forensic Science Service officer was called to give evidence about the samples, but may have been wrong in giving an opinion on how the DNA must have reached the knives, he said.

"The principle issue is whether or not the reporting officer was entitled to give the opinion she did, namely that the most likely explanation for DNA profiles on the two exhibits was that the appellants were handling those knives at the time that they broke," he said.

He continued: "In reaching the opinion that David Reed was most likely holding a knife, the officer was seeking to displace and ignore the other evidence in the case, the scientific evidence."

Pathologists had agreed that there was no evidence of any twisting of knives in Mr Hoe's wounds, while a metallurgist had stated that, in order for such knives to break, such motion or contact with a hard surface would be needed, he said.

And although the officer said she had not ruled out methods of the DNA reaching the knives without them ever touching them - so-called "secondary transfer" - she had told the jury that it was "unrealistic".

That was "very much more" than simply telling the jury that it was less likely than them having come into physical contact with the weapons, he said.

If the officer was not entitled to give the opinion she did, then the convictions are "unsafe" and must be quashed, Mr Hill told Lord Justice Thomas, Mr Justice Kitchin and Mr Justice Holroyde.

Had the officer been restricted to giving her opinion solely on the chance of random DNA matches, then that may have been excluded from the trial, also impacting on the safety of the convictions, he continued.

Mr Hill said that a challenge to the technique of "low-copy number" DNA profiling used in the case had been dropped at the eleventh hour after further testing of the exhibits revealed larger quantities of biological material than expected.

The appeal, expected to last four days, had started in dramatic circumstances earlier this morning when both men stood up without a word to the judges or barristers and walked out of court.

But they were back in court after the lunchtime adjournment when the judges began to hear more detailed argument and evidence relating to the DNA issue.

Lawyers for the Crown will argue that, even if the judges find that there were problems in the way the DNA evidence was dealt with, the convictions can be upheld on the basis of other "circumstantial" evidence.

The hearing, due to last four days, continues.