Fred Crawford 'blood signature' legend challenged Published duration 27 September 2012

An Ulster Covenant signature believed to have been written in blood almost certainly wasn't, according to a test carried out on behalf of the BBC.

The forensic science test was carried out by Dr Alastair Ruffell of Queen's University, Belfast.

"I'm 90% sure this isn't blood, but there is that margin of error," he said.

Major Fred Crawford wrote on his own copy of the Covenant oath: "I signed at 3:45 in City Hall in my own blood".

Dr Ruffell said that it was almost certain that it was not blood but added there was a margin of error because "this material has been uncontrolled for 100 years".

Major Crawford's signature is still a rich red colour today.

Unconvinced

For the test, carried out for the BBC's Knowledge and Learning team, Major Crawford's signature was injected with a small amount of Luminol.

This substance reacts with iron in blood's haemoglobin to produce a blue-white glow.

The test is very sensitive and can detect tiny traces even in old samples.

"Some years ago we did a test in the Colorado desert where they put some blood on some rocks and we went back ten years later and we were able to find the blood using the Luminol test," said Dr Ruffell.

"The iron in the blood degrades very slowly."

Unionist MLA Robin Swann is unconvinced by the results of the test.

"I'm confident enough that the 10% is enough for me to say that Fred Crawford signed the Ulster Covenant in his blood," he said.