Barnabei protested his innocence

The US State Department has issued a warning to US citizens in Italy to be on their guard against revenge attacks.

Barnabei protested his innocence to the end.

The United States Supreme Court had turned down two appeals hours beforehand.

The Governor of Virginia rejected a plea for clemency on Monday after further DNA tests apparently confirmed Mr Barnabei's guilt.

'Retribution' threats

The execution has drawn enormous attention from Italy, where Mr Barnabei's mother lives.

Journalists reported from outside the state prison in the hours and minutes leading up to his death; candlelit vigils were held across Italy.

Italian Prime Minister Giuliano Amato wrote to one newspaper describing the death penalty as "collective revenge" .

Hours before the execution took place, the US State Department issued a warning to American citizens in Italy.

It said that it had received anonymous threats of retribution against Americans should the death penalty be carried out.

It has warned citzens to take the precautions they think necessary for their safety.