In addition to the DNA tests, the SIG team investigated the accused being tried in the Benazir Bhutto case in Adiala jail and questioned Saud Aziz, the then Rawalpindi City Police Officer, and DCO Irfan Elahi on Thursday.
Sources said the team conducted the DNA test to verify the presence of the suicide bomber at the residence of Hasnain Gul in Rawalpindi, who is being suspected as 'facilitator' in the case.
The investigators believe that the suicide bomber who blew himself up near Benazir Bhutto's bullet-proof vehicle outside Liaquat Bagh on Dec 27, 2007, had been staying at the residence of Hasnain Gul.
The team has also investigated the suspects being tried in the Benazir Bhutto case to complete the charge-sheet because they believe that delay in prosecution is giving benefit to the suspects.
Saud Aziz said that he had ordered hosing down of the crime scene by using his discretionary powers, denying that anybody had asked him to do so.
He said that police had collected important evidence and later washed only the place that was splattered with blood.
Mr Aziz denied that any important evidence was destroyed by police.
He presented the record of suicide bombings in Lahore, Peshawar and Rawalpindi in which less evidence had been collected from the crime scene compared with the Dec 27 bombing.
