The forensic science agency responsible for gathering evidence for investigation into the Model Town clashes said relevant evidence was no longer usable.
On June 17, activists of Pakistan Awami Tehreek (PAT) and policemen had fought pitched battles in the streets which gave at least 14 party workers dead and scores of others wounded.
In a report presented to a judicial direction, the forensic agency said material evidence such as bullet holes and shattered glass was removed from the crash site in post-riot cleanup. The office also told the delegation that it bears no further part to play in the investigation.
Members of the agency had visited the site of the bloodshed along with the joint probe team, which was put up by the judicial committee.
The clashes had erupted in the early hours of June 17 and continued for upwards to 14 hours. The opposition had begun when a 15-member police team tried to take away the barriers in front of PAT chief Dr Tahirul Qadri’s house and the Minhaj International Secretariat.