Even if an iota of doubt comes in a case of death penalty, the award must be commuted, he added.
Mr Burney, who held dicussions with the Punjab State Human Rights Commission here, said he would cross-examine the witnesses who deposed against Sarabjit Singh in the serial blasts cases, to reach the conclusion.
Mr Burney had stated that he would soon take up the issue of Sarabjit's release with the newly-formed government in Pakistan.
He had assured the family of Sarabjit Singh that he would fight till the end to achieve the re-union of the family, which has undergone untold suffering for the past 17 years.
However, he had also stated in several fora that he had no sympathy for terrorists.