Four more individuals, who had been recently in contact with Jamiat-i-Ulema Islam-Sami (JUI-S) chief Maulana Sami-ul-Haq, were questioned as a part of the probe into the assassination of the religious leader.
According to sources, the four people had been in contact with the slain JUI-S chief in the weeks before he was killed
The investigation team collected a number of evidence from the crime scene, including, hair of three lengths, the bed sheet with blood on it and three glasses from the spot.
The hair and blood samples were sent to a forensic laboratory for DNA testing.
The police officials have searched the gardens of neighbouring houses and the surrounding hilly areas to trace the murder weapon and other evidence which may help identify the killer.
The medical examination report, from the private hospital where Maulana Samiul Haq was taken and declared dead, has also been obtained by the police.
According to doctors, the former senator died an hour prior to the time when his body was brought to the hospital. The medical reports include an ECG, x-rays and details of the stab wounds.