Bogota - The ruling Liberal Party candidate, Mr Horacio Serpa, was running neck and neck with the Conservative Party-backed Mr Andres Pastrana as results poured in from Colombia's violent presidential elections yesterday. Official returns, with 60.5 per cent of the ballots counted, gave Mr Serpa 35.8 per cent of the vote, just ahead of Mr Pastrana with 35.1 per cent. Ms Noemi Sanin, independent, had 25.1 per cent.